RobersonCreekTMDLFinal

Total Maximum Daily Load (TMDL)
For Total Phosphorus

Final Report
August 2003
(Approved January 2004)

Roberson (Robeson) Creek
Subbasin 03-06-04
Cape Fear River Basin
North Carolina

Prepared by:
NC Department of Environment and Natural Resources
Division of Water Quality
Water Quality Section
1617 Mail Service Center
Raleigh, NC 27699-1617
[phone]
Roberson (Robeson) Creek TMDL Final Report

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INDEX OF TMDL SUBMITTAL

1. 303(d) List Information

State North Carolina
County Chatham
Basin Cape Fear River Basin

303(d) Listed Waters
Name of Stream Description Class Index # Subbasin Miles
Roberson Creek From a point 0.3 miles upstream of
mouth to B. Everett Jordan Lake,
Haw River
WS-IV, NSW, C 16-38-(5) 30604 0.6

14 digit HUC or Cataloging Unit(s) 03030002060030
Area of Impairment 0.6 miles
WQS Violated Chlorophyll a
Pollutant of Concern Total Phosphorus
Sources of Impairment Point and nonpoint sources from entire watershed

2. Public Notice Information

A draft of the Roberson Creek TMDL was publicly noticed through various means, including
notification in the local newspaper, The Chatham Record, on June 19, 2003. DWQ electronically
distributed the draft TMDL and public comment information to known interested parties. The
TMDL was also available from the Division of Water Quality’s website at
http://h2o.enr.state.nc.us/tmdl/draft_TMDLs.htm during the comment period beginning June 19
and ending July 21. A public meeting was held on July 15 at the Chatham County Agricultural
Center Auditorium in Pittsboro. At this meeting, staff presented the TMDL and answered
questions. In addition to DWQ staff, 14 people attended the meeting.

Did notification contain specific mention of TMDL proposal? Yes
Were comments received from the public? Yes
Was a responsiveness summary prepared? Yes. A responsiveness summary is found in Chapter
10 of the TMDL report.
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3. TMDL Information

Critical condition: Dry hydrologic conditions; summer algal growing season
Seasonality: TMDL is based on meeting the target standard during the critical summer growing
season. The TMDL is applied to the period, April through October. Weather related variability
during the model period is incorporated. Basing the TMDL on this warm weather period will also
protect Roberson Creek during the cold weather period (November – March).

Development tools: FLUX, BATHTUB, SWAT
Supporting documents: Total Maximum Daily Load (TMDL) For Total Phosphorus, NC
Division of Water Quality (2003)

TMDL
Total mass daily load allocation of total phosphorus in kilograms (kg).
Source Types TMDL for
Summer
(April-October)
%
Reduction

1. Non-point source
Urban
Forest
Pasture/Hay lands

2. Point source
WWTP

Total

44
--
--

146

190

71
0
0

71

71

Load allocation at critical condition: 190 kg TP/ summer (0.89 kg TP/day/summer)
Waste load allocation (WLA): 146 kg TP/summer (0.68 kg TP/day/summer)
Load allocation (LA): 44 kg TP/summer (0.21 kg TP/day/summer)
Margin of Safety (applied to the water quality criteria): An explicit margin of safety of 7.9 µg/L
chlorophyll a based on meeting the lower 80% confidence interval of receiving water model
predictions.
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TABLE OF CONTENTS
1 Introduction.............................................................................................................................1
1.1 Watershed Description....................................................................................................3
1.2 Water Quality Target......................................................................................................6
1.3 Water Quality Assessment..............................................................................................9
2 Source Assessment................................................................................................................14
2.1 Point Source Assessment..............................................................................................15
2.2 Non-Point Source Assessment......................................................................................17
2.2.1 Agricultural Lands....................................................................................................17
2.2.2 Urban lands ..............................................................................................................18
3 Modeling Approach...............................................................................................................19
3.1 Receiving Water Model................................................................................................19
3.1.1 Model Framework....................................................................................................19
3.1.2 Model Setup .............................................................................................................20
3.1.2.1 Segment Morphometry....................................................................................20
3.1.2.2 Climate Input and Atmospheric Loads............................................................21
3.1.2.3 In-Lake Concentrations ...................................................................................22
3.1.2.4 Tributary Loading Estimates ...........................................................................22
3.1.3 BATHTUB Calibration............................................................................................30
3.1.4 BATHTUB Verification...........................................................................................33
3.2 Watershed Loading Model ...........................................................................................37
3.2.1 Model Setup .............................................................................................................38
3.2.1.1 Model Inputs....................................................................................................38
3.2.2 Model Calibration.....................................................................................................39
3.2.2.1 Flow.................................................................................................................39
3.2.2.2 Total Phosphorus.............................................................................................41
3.2.3 Model Output ...........................................................................................................43
4 Allocation..............................................................................................................................45
4.1 Total Maximum Daily Load (TMDL)..........................................................................45
4.2 Critical Conditions........................................................................................................47
4.3 Seasonal Variation........................................................................................................47
4.4 Model Uncertainty and Margin of Safety.....................................................................48
4.5 Waste Load Allocation .................................................................................................49
4.6 Load Allocation............................................................................................................49
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5 Implementation Plan..............................................................................................................50
6 Stream Monitoring ................................................................................................................51
7 Future Efforts ........................................................................................................................51
8 Public Participation ...............................................................................................................51
9 Further Information...............................................................................................................52
10 Responsiveness Summary.....................................................................................................53
11 References.............................................................................................................................62

Appendix I. Water quality data collected during the Roberson Creek TMDL Study (2000-2002).
Appendix II. DWQ ambient data collected at RC10.
Appendix III. Water column profile data for the Roberson Creek Cove.
Appendix IV. Stream flow inputs for FLUX.
Appendix V. FLUX water quality sample input files.
Appendix VI. FLUX output files – 2001.
Appendix VII . FLUX output files – 2002
Appendix VIII. BATHTUB calibration input files and output.
Appendix IX. BATHTUB verification files.
Appendix X. BATHTUB phosphorus loading scenarios.
Appendix XI. Monthly average depth of irrigated water on the wastewater spray fields of
Townsend Foods Inc.
Appendix XII. Daily average temperature and precipitation recorded in the Siler City Airport.
Appendix XIII. Daily average flow and concentration of total Phosphorus discharged from the
Pittsboro WWTP to Roberson Creek during 2001.
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TABLES

Table 1.1. Summary statistics (mean, median, standard error, and number of samples N) for
nutrients and chlorophyll a samples collected at the Roberson Creek ambient station year
round......................................................................................................................................10
Table 1.2. Summary statistics for physicochemical properties of the Roberson Creek Cove
(2001-2002) based on pooled surface samples from RC10 and RC11 collected during the
period, April - October. N = # of samples.............................................................................11
Table 2.1. Average concentration of total phosphorus (mg/l) in Townsend irrigation wastewater
in 2001...................................................................................................................................18
Table 3.1 FLUX equations used for calculation of tributary loads to Roberson Creek (from
Walker 1996).........................................................................................................................26
Table 3.2. Estimated summer flow-weighted concentrations for the Roberson Creek Cove using
adjusted FLUX results (April through October)....................................................................30
Table 3.3. Chlorophyll a models within BATHTUB described according to limiting factors. ....32
Table 3.4. Adjusted parameters for the model calibration............................................................41
Table 3.5. Estimation of mean and standard error for the flow rates............................................41
Table 3.6. Estimation of mean and standard error for TP (kg/day) at the station RC 8................42
Table 3.7. Total phosphorus loads (kg) delivered to station RC 8 during 2001............................44
Table 4.1. Total mass daily load allocation of total phosphorus in kilograms (kg). .....................49

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FIGURES

Figure 1.1. Map of Roberson Creek watershed (DWQ subbasin 030604; 14 digit HUC
03030002060030)....................................................................................................................5
Figure 1.2. Land use map of the Roberson Creek watershed (2002; provided by Angela Moreland
of the NCSU Water Quality Group). Landuse digitized by orthoquad and field verification
of landuse using orthophotos. Categories are based on Anderson landuse classifications.....6
Figure 1.3. Color infrared photography (1998 DOQQ) of the Roberson Creek cove......................7
Figure 1.4. Total nitrogen to total phosphorus ratios (TN:TP) by mass for the ambient station
(RC10) on Roberson Creek. For reference, the Redfield ratio is 7.2 (by mass)......................9
Figure 1.5. Location of sampling stations and subwatersheds in the Roberson Creek watershed
during the TMDL study.........................................................................................................12
Figure 1.6. Boxplots of nutrient concentrations (total phosphorus-top; total nitrogen-bottom) for
stations RC8 and RC10 during the April - October periods of 2001 and 2002. The boxes
represent the median (dashed line), quartiles and outliers. One TP value (0.84 mg/L) from
5/30/2001 at RC8 is not shown on the graph.........................................................................13
Figure 1.7. Chlorophyll a concentrations at RC10 and RC11 for the period 2001 through 2002.14
Figure 2.1. Box plot showing total phosphorus concentration at the stations in Roberson Creek
Watershed. The stations are arranged from upstream to downstream. The prefix S stands
for station; RC for Roberson Creek; CC for Camp Creek; and TC for Turkey Creek. The
line connects the means at each station. ................................................................................16
Figure 3.1. Comparison of estimated Roberson Creek stream flow at RC8 using Tick Creek and
Rocky River gages (adjusted for wastewater treatment plant flow) with instantaneous flow
data collected at RC8.............................................................................................................23
Figure 3.2. Plot of daily flow record (April – October 2001) and dates of sample collection (red
squares) for RC8 on Roberson Creek. The symbols indicate the daily flows on the dates of
sample collection. Flow units are hm3/yr (= cfs * 0.893).....................................................27
Figure 3.3. Plot of sample flow (hm3/yr) versus total phosphorus concentration (mg/m3) during
the period April through October, 2001 at RC8....................................................................28
Figure 3.4. Plot of daily flow record (April – October 2002) and dates of sample collection (red
squares). The symbols indicate the daily flows on the dates of sample collection. Flow
units are hm3/yr......................................................................................................................29
Figure 3.5. BATHTUB calibration for Roberson Creek Cove (April – October 2001). Values
plotted are observed and estimated means +/- one standard error.........................................33
Figure 3.6. BATHTUB verification for Roberson Creek Cove using data inputs from April –
October 2002. Values plotted are observed and estimated means +/- one standard error....35
Figure 3.7. BATHTUB verification for Roberson Creek Cove using data inputs from April –
September 2002. Values plotted are observed and estimated means +/- one standard error.
...............................................................................................................................................36
Figure 3.8. Comparison of observed flow and simulated flow at the ambient station RC 8 for
2001.......................................................................................................................................40
Figure 3.9. Total load of total phosphorus as estimated by the load regression method and the
SWAT model for the study year 2001...................................................................................43
Figure 4.1. Load reduction scenarios for total phosphorus (TP) in the Roberson Creek Cove.
TMDL target standard is to have less than or equal to 10% of the samples above the
chlorophyll a standard of 40 µg/L. The margin of safety (MOS) is based on an 80%
confidence limit of model predictions...................................................................................46

Roberson (Robeson) Creek TMDL Final Report

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1 Introduction

Roberson (Robeson) Creek 1 is currently on North Carolina’s 303(d) list of impaired waters for
chlorophyll a (chl a) violations in 0.6 miles of the lower reach near its confluence with the Haw
River arm of Jordan Lake. The main stem of Roberson Creek is also on the 303(d) list for
biological impairment from a point 0.7 miles downstream of SR 2159 to upstream of the mouth.
In addition, Pittsboro Lake, located on the upper portion of Roberson Creek in the Town of
Pittsboro, is on the 303(d) list due to aquatic weeds. This report focuses on impairment related to
chl a in the most downstream portion of Roberson Creek, referred to hereafter as the Roberson
Creek Cove. The report determines sources and allowable loads of total phosphorus, which has
been identified as the factor most limiting the growth of algae as measured by chl a.

Section 303(d) of the Clean Water Act (CWA) requires states to develop a list of waters not
meeting water quality standards or which have impaired uses. This list, referred to as the 303(d)
list, is submitted biennially to the U.S. Environmental Protection Agency (EPA) for review.

The 303(d) process requires that a Total Maximum Daily Load (TMDL) be developed for each of
the waters appearing on Part I of the 303(d) list. The objective of a TMDL is to estimate
allowable pollutant loads and allocate to known sources so that actions may be taken to restore
the water to its intended uses (USEPA, 1991). Generally, the primary components of a TMDL, as
identified by EPA (1991, 2000a) and the Federal Advisory Committee (FACA, 1998) are as
follows:

Target identification or selection of pollutant(s) and end-point(s) for consideration. The pollutant
and end-point are generally associated with measurable water quality related characteristics that
indicate compliance with water quality standards. North Carolina indicates known pollutants on
the 303(d) list.

1 There are several spellings of this waterbody. A 1930’s USDA SCS soil map refers to the creek
as Robeson Creek as do the NC Department of Transportation road signs marking access points to
the creek. However, USGS and DWQ have spelled the creek as Roberson Creek. The spelling
used by USGS will be used in the main body of the report.

Roberson (Robeson) Creek TMDL Final Report

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Source assessment. All sources that contribute to the impairment should be identified and loads
quantified, where sufficient data exist.

Reduction target. Estimation or level of pollutant reduction needed to achieve water quality goal.
The level of pollution should be characterized for the waterbody, highlighting how current
conditions deviate from the target end-point. Generally, this component is identified through
water quality modeling.

Allocation of pollutant loads. Allocating pollutant control responsibility to the sources of
impairment. The wasteload allocation portion of the TMDL accounts for the loads associated
with existing and future point sources. Similarly, the load allocation portion of the TMDL
accounts for the loads associated with existing and future non-point sources, stormwater, and
natural background.

Margin of Safety. The margin of safety addresses uncertainties associated with pollutant loads,
modeling techniques, and data collection. Per EPA (2000a), the margin of safety may be
expressed explicitly as unallocated assimilative capacity or implicitly due to conservative
assumptions.

Seasonal variation. The TMDL should consider seasonal variation in the pollutant loads and
end-point. Variability can arise due to stream flows, temperatures, and exceptional events (e.g.,
droughts, hurricanes).

Critical Conditions. Critical conditions indicate the combination of environmental factors that
result in just meeting the water quality criterion and have an acceptably low frequency of
occurrence.

Section 303(d) of the CWA and the Water Quality Planning and Management regulation
(USEPA, 2000a) require EPA to review all TMDLs for approval or disapproval. Once EPA
approves a TMDL, then the waterbody may be moved to Category 4a of the Integrated Report.
Waterbodies remain in Category 4a until compliance with water quality standards is achieved.
Where conditions are not appropriate for the development of a TMDL, management strategies
may still result in the restoration of water quality.
Roberson (Robeson) Creek TMDL Final Report

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The goal of the TMDL program is to restore designated uses to water bodies. Thus, the
implementation of nutrient controls throughout the watershed will be necessary to restore uses in
the Roberson Creek Cove. Although an implementation plan is not included as part of this
TMDL, reduction strategies for point and nonpoint sources will be needed. The involvement of
local governments and agencies will be critical in order to develop implementation plans and
reduction strategies. Development of an implementation plan will begin during public review of
the TMDL. The NCSU Water Quality Group will be developing general and site-specific
implementation plans.

1.1 Watershed Description

Roberson Creek flows in an easterly direction 10.9 miles from its origins southwest of the Town
of Pittsboro to its mouth at the Haw River arm of Jordan Lake (Figure 1.1). Located entirely
within the Pittsboro town limits and its extra-territorial jurisdiction, the 28.6-mi 2, piedmont
watershed is approximately 73% forested, 9% agricultural, and 16% urban (NCSU Water Quality
Group 2002; Figure 1.2). Part of the upper watershed consists of residential, commercial, and
industrial development surrounding the Town of Pittsboro. The area outside of the corporate
limits of Pittsboro consists primarily of low density residential development, agriculture, and
forestland. The Pittsboro wastewater treatment plant (WWTP; NPDES permit #NC0020354)
discharges into Roberson Creek 7.0 miles upstream from Jordan Lake. The lower watershed,
from the Pittsboro WWTP to Jordan Lake consists mostly of undeveloped forestland, low density
residential development, pasture and hayfields.

The Roberson Creek watershed is located within the Carolina Slate Belt, which consists of
predominately metavolcanic and metigneous rocks. This geology typically yields low base flows
compared to other hydrologic areas (Giese and Mason 1993). Roberson Creek descends
approximately 230 feet from its headwaters to Jordan Lake (10.9 miles), with approximately 100
feet of descent in the last three miles. This gradient is typical of streams in the Haw River basin.

Surface water classifications are designations applied to surface water bodies that define the best
uses to be protected within these waters (for example swimming, fishing, drinking water supply)
and carry with them an associated set of water quality standards to protect those uses. Roberson
Roberson (Robeson) Creek TMDL Final Report

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Creek is classified as a water supply watershed (WS-IV), nutrient sensitive (NSW), and a class C
waterbody. The waters are protected for drinking water supply, secondary recreation, fishing,
wildlife, fish and aquatic life propagation and survival, agriculture and other uses suitable for
Class C. Secondary recreation includes wading, boating, and other uses involving human body
contact with water where such activities take place in an infrequent, unorganized, or incidental
manner.

5

Figure 1.1. Map of Roberson Creek watershed (DWQ subbasin 030604; 14 digit HUC 03030002060030).
Roberson Creek TMDL Final Report

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Figure 1.2. Land use map of the Roberson Creek watershed (2002; provided by Angela Moreland
of the NCSU Water Quality Group). Landuse digitized by orthoquad and field verification
of landuse using orthophotos. Categories are based on Anderson landuse classifications.

1.2 Water Quality Target

Roberson Creek appears on North Carolina’s 303 (d) list for chl a. This downstream portion of
Roberson Creek is partially lentic in nature and can be considered a small cove on the Haw River
arm of Jordan Lake (Figure 1.3). Chlorophyll a, the dominant pigment in algal cells, is a useful
surrogate for algal biomass.

Roberson Creek TMDL Final Report

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Figure 1.3. Color infrared photography (1998 DOQQ) of the Roberson Creek cove.

The following North Carolina standard (15A NCAC 02B.0211) applies to all freshwater surface
waters:

Chlorophyll a (corrected): not greater than 40 µg/l for lakes, reservoirs, and other
waters subject to growths of macroscopic or microscopic vegetation not designated as
trout waters, and not greater than 15 µg/l for lakes, reservoirs, and other waters subject
to growths of macroscopic or microscopic vegetation designated as trout waters (not
applicable to lakes and reservoirs less than 10 acres in surface area); the Commission or
its designee may prohibit or limit any discharge of waste into surface waters if, in the
opinion of the Director, the surface waters experience or the discharge would result in
growths of microscopic or macroscopic vegetation such that the standards established
Outlet
Haw River Arm
of Jordan Lake
Roberson Creek Cove
Roberson Creek TMDL Final Report

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pursuant to this Rule would be violated or the intended best usage of the waters would be
impaired.

The TMDL target is based on the frequency of algal blooms: no more than 10% of samples
collected in a specified area and time should be above 40 µg/L chl a. This target, based on
USEPA guidance for use support determination, was also selected for NC’s Neuse River Estuary
TMDL for Total Nitrogen approved by EPA in 2002 (Office of Water 1997).

Algal growth is affected by numerous biotic and abiotic factors including light availability, flow
and water velocity, nutrients (particularly nitrogen (N) and phosphorus (P)), grazing, and other
influences. Nutrient controls are the most common focus of management schemes for reducing
excessive algal growth. While the chemical factors that determine algal biomass can vary by
waterbody and season, P is often cited as a limiting factor in many lakes and reservoirs (Wetzel
2001). When P is limiting, reductions in P will decrease algal productivity because the species is
the nutrient in greatest demand in relation to supply.

Phytoplankton communities exhibit varying nutrient requirements but on a whole require N and P
in amounts approximately equal to Redfield’s (1958) molar ratio of 16N:1P (7.2N:1P by mass).
Deviations from this ratio have been used to infer nutrient limitation without the benefit of
nutrient bioassay experiments or algal growth potential tests. Ratios less than the Redfield ratio
generally suggest P limitation. In Roberson Creek, N:P ratios suggest a stronger P limitation than
N. During the period 1997 - 2002, most values (interquartile range) of the TN:TP ratio by mass
fell between 7 and 14 (Figure 1.4). This ratio was higher during the latter part of that period.

This TMDL will assess the amount of total P (TP) reduction necessary to comply with the chl a
target. The focus on P is based on the assumption that P will ultimately control growth. In
addition, P is typically more cost-effective to remove from point sources and reductions will drive
the cove to an increasingly P limited state (Thomann and Mueller 1987, Wetzel 2001).
Roberson Creek TMDL Final Report

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Figure 1.4. Total nitrogen to total phosphorus ratios (TN:TP) by mass for the ambient station
(RC10) on Roberson Creek. For reference, the Redfield ratio is 7.2 (by mass).

1.3 Water Quality Assessment

Historical data from the DWQ ambient monitoring station (B2450000), located in the Roberson
Creek Cove (Figure 1.5), indicates elevated nutrient levels, high algal productivity and frequent
nuisance algal blooms. From 1997 to 2002, mean total phosphorus concentrations ranged from
0.11 to 0.16 mg/L (Table 1.1). The cove can be considered eutrophic for TP and
eutrophic/mesotrophic for TN, based on its ranking among findings of the OECD eutrophication
program (USEPA 2000). Likewise, trophic state indices (Carlson 1977) calculated for 2001 and
2002 suggest the waterbody is also in a eutrophic state with Trophic State Index (TSI) values
between 50 and 70.

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Roberson Creek TMDL Final Report

Table 1.1. Summary statistics (mean, median, standard error, and number of samples N) for
nutrients and chlorophyll a samples collected at the Roberson Creek ambient station year
round.

1997 1998 1999 2000 2001 2002 1
Mean .163 .121 .133 .116 .126 .105
Median .150 .115 .140 .09 .100 .100
SE .02 .019 .009 .015 .024 .014 TP (mg/L)
N 10 12 12 9 18 15
Mean 1.18 .928 1.00 .867 1.50 1.50
Median 1.14 .755 1.08 .880 1.29 1.24
SE .12 .145 .074 .072 .127 .263 TN (mg/L)
N 10 12 12 9 18 15
Mean -- 29.7 48.8 61.8 38.7 31.7
Median -- 26.0 45.0 44.0 31.0 30.0
SE -- 7.6 18.9 28.0 5.9 6.8 Chl a (µg/L) 2
N -- 7 4 4 13 15
Hydrologic Condition Average Dry Wet Dry Dry Dry
Flow (% of Long
Term Mean) 3 82% 140% 83% 48% 26% 26%

1 Summary statistics for 2002 are for Jan – Oct.
2 Chlorophyll a data for 1998-2000 are reported as uncorrected for pheophytin, which may overestimate
the actual corrected value.
3 Based on 43 year record at the Tick Creek gage.

When indicators of dissolved oxygen (DO) and pH at the ambient station suggest potential
blooms conditions, phytoplankton samples are collected by DWQ for biovolume and community
analysis. Of the 31 phytoplankton samples collected between 1987 and 2002, 97% were
considered blooms (NCDWQ 2002). The magnitude ranged from mild (10,000-20,000 units/ml)
to severe (>30,000 units/ml). Algal densities ranged from 12,000 to 244,400 units/ml.

A special study was conducted from December 2000 through August 2002 in support of TMDL
development (NCDWQ 2002). There were two stations located in the cove (RC10 and RC11)
and 12 stations located upstream throughout the watershed (Figure 1.5). Sample parameters for
the study consisted of nutrients (except for orthophosphate), biochemical oxygen demand, DO,
pH, temperature, and conductivity. Flow measurements were taken where possible during each
sampling event and a stage-flow relationship was developed at RC8 in the lower study area. At
two of the sites (RC10 and RC11) located in the cove, additional parameters or analyses included
algal community analysis and depth integrated physical profiles.

Roberson Creek TMDL Final Report

Warm weather period data did not reveal strong vertical temperature stratification or frequent
anoxic bottom waters in the cove. Average pH and DO concentrations reveal elevated algal
productivity levels (Table 1.2). Secchi depth, a measure of water column transparency, ranged
from 0.35 to 0.53 m, averaging 0.40 m and 0.37 m, respectively during 2001 and 2002.

Table 1.2. Summary statistics for physicochemical properties of the Roberson Creek Cove
(2001-2002) based on pooled surface samples from RC10 and RC11 collected during the
period, April - October. N = # of samples.

Temp.
(oC)
DO
(mg/L)
pH (std.
units)
Conductivity
(umhos)
Secchi
Depth (m)
Mean 24.5 10.8 8.78 221.7 0.40
Median 26.0 11.0 8.80 220.0 --
SE 1.5 0.74 0.35 6.96 0.05 2001
N 15 15 15 11 2
Mean 26.3 9.78 8.42 289.3 0.37
Median 27.6 10.6 8.80 305.5 0.34
SE 1.41 0.86 1.41 50.7 0.04 2002
N 12 12 14 8 6

Nutrient concentrations (TP and TN) for RC8, the most downstream tributary station, and RC10,
the ambient station in the cove are shown in Figure 1.6. Concentrations in the cove were
generally lower than the those at RC8. This may be attributable to factors such as sedimentation,
algal uptake and dilution.

Time series data for chl a (modified non-acidification method) in Figure 1.7 indicates frequent
exceedences of 40 µg/L during both years, primarily during summer and fall. Most values exceed
20 µg/L. Chlorophyll a concentrations in the cove averaged 32.9 µg/L and 39.1 µg/L (medians
were 25.8 µg/L and 33.8 µg/L ) during the period April through October of 2001 and 2002,
respectively. Data collected during 2001 and 2002 (primarily 2001) are used for modeling and
establishing the TMDL.

RC4 Roberson Creek at 15/501 Pittsboro
RC5ups Roberson Creek WWTP upstream monitoring site
RC5eff Roberson Creek WWTP effluent outfall site (#NC0020354)
RC5dns Roberson Creek WWTP downstream monitoring site
TC1
TC2 Turkey Creek at SR1012 (downstream from Townsend Foods)
TC3 Turkey Creek 100 feet upstream Roberson/Turkey confluence
CC2lft Camp Creek upstream of tributary draining Townsend Foods
CC2rt Un-named tributary draining Townsend Foods property
CC bdg Camp Creek at SR1012 (downstream from Townsend Foods)
CC3
RC8 Roberson Creek at flow rating site near Lucian Bland Rd.
RC10 Roberson Creek arm at boat ramp (ambient site #B2450000)
RC11 Roberson Creek arm at 0.5 mi downstream from RC10

Figure 1.5. Location of sampling stations and subwatersheds in the Roberson Creek watershed during the TMDL study.
Roberson (Robeson) Creek TMDL Final Report

Figure 1.6. Boxplots of nutrient concentrations (total phosphorus-top; total nitrogen-bottom) for
stations RC8 and RC10 during the April - October periods of 2001 and 2002. The boxes
represent the median (dashed line), quartiles and outliers. One TP value (0.84 mg/L) from
5/30/2001 at RC8 is not shown on the graph.
Roberson (Robeson) Creek TMDL Final Report

Figure 1.7. Chlorophyll a concentrations at RC10 and RC11 for the period 2001 through 2002.

2 Source Assessment
Nutrients are transported from throughout the watershed to Roberson Creek in two primary ways:
runoff and direct point source. Runoff from various land uses contributes nutrients to the
impaired waterbody primarily during storm events. The other major source of nutrients is the
Town of Pittsboro Wastewater Treatment Plant.

The DWQ monitors a suite of water quality parameters, including nutrients, at an ambient station
on Roberson Creek Cove on a monthly basis (RC10). During the special TMDL study for the
Roberson Creek watershed, there were five stations on the creek and seven stations on the
tributaries of the creek (Figure 1.5). The station, RC8, was responsible for delivering the
majority TP from the Roberson Creek watershed down to the cove. The longitudinal distribution
Roberson (Robeson) Creek TMDL Final Report

of TP from near downtown Pittsboro to the watershed outlet (RC8) is given in Figure 2.1. The
data collected for the study is presented in Appendix 1.

2.1 Point Source Assessment

Point sources are typically those regulated under National Pollutant Discharge Elimination
System (NPDES) programs. Permitted discharge facilities measure nutrient levels in their
effluent at a frequency based on facility class and waste type. Currently, there is one NPDES
permitted point source, the Pittsboro Waste Water Treatment Plant (WWTP), in the Roberson
Creek watershed. The plant discharges domestic waste in the watershed, five miles upstream
from RC8. The plant is permitted to discharge 0.75 MGD (monthly average) of effluent water
with TP concentration of 2.0 mg/liter (quarterly average). There are no regulated MS4 areas
within the watershed.

In 2001, the annual average concentration of TP before reaching the WWTP site (S2_RC5eff)
was 0.07 mg/l (Figure 2.1) RC5_eff is the site at the outlet of the effluent plant. TP measured at
the site is the concentration of the effluent, not the concentration of the water of the creek. The
average concentration peaked to 2.5 mg/l at the WWTP site, which was higher than the permitted
concentration 2 mg/l. As the water routed to downstream, the concentration gradually reduced to
0.92 mg/l at the station S3_RC 5dns. The concentration of TP at the WWTP site ranged from 0.2
mg/l to 9.0 mg/l. Out of 16 samples collected in 2001, 8 samples indicated TP concentration
below 1.9 mg/l and four indicated above 3.2 mg/l.
Roberson (Robeson) Creek TMDL Final Report

TP
(
m
g
/
l
)
0.001
0.01
0.006
0.004
0.002
0.1
0.06
0.04
0.02
1
0.6
0.4
0.2
10
6
4
2
1
S1_RC5up S2_RC5eff S3_RC5dns S4_TC3 S5_CC3 S6_RC8out
Ambient Stations

Figure 2.1. Box plot showing total phosphorus concentration at the stations in Roberson Creek
Watershed. The stations are arranged from upstream to downstream. The prefix S stands
for station; RC for Roberson Creek; CC for Camp Creek; and TC for Turkey Creek. The
line connects the means at each station.

Roberson (Robeson) Creek TMDL Final Report

2.2 Non-Point Source Assessment

Non-point sources are diffuse sources that typically cannot be identified as entering a water body
at a single location. Agriculture and urban lands were the two major non-point sources of TP in
the watershed (Figure 1.2). Agriculture land sources included cropland, pasture/hay land, and
forested land. Urban land sources were streets, lawns, roofs, driveways, parking lots, and sewer.

2.2.1 Agricultural Lands

Sources of TP in agriculture lands are chemical fertilizer, wastewater, and litter fall. In the
watershed, a majority of farmers practiced animal grazing and hay cultivation during 2001. They
applied nitrogen fertilizer, 33-0-0, twice in a year at a rate of 168 kg/ha (source: Mr. Henry Outz,
Chatham Soil and Water Conservation District). The first application began in the second week
of March and the second application in the second week of September. Hay was harvested in
May.

Townsend Foods, Inc. owns about 600 acres of land and manages a 16-acre lagoon. Most of the
land is used to graze a modest herd of cattle except in the waste lagoon spray fields The company
has acquired a DWQ permit (WQ0001755) and is allowed to operate the spray fields (130 acres)
with no discharge to surface waters.

Townsend Foods irrigated the spray fields three to four times a month during 2001 (Source:
DWQ Permit #WQ0001755). The amount of irrigation was estimated to be 2.6 mm per month.
The concentration of TP in the irrigated lagoon wastewater was estimated to be 11 mg/l (3 kg/ha)
(Table 2.1). Phosphorus from the irrigated wastewater, transported via surface and sub-surface
runoff, appears to have moved into Turkey Creek and Camp Creek (Figure 2.1). These results
suggest that the spray fields owned by Townsend Foods Inc. may have delivered considerable
amounts of P to Roberson Creek during storm events in 2001.

Roberson (Robeson) Creek TMDL Final Report

Table 2.1. Average concentration of total phosphorus (mg/l) in Townsend irrigation wastewater
in 2001.

Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec
NA NA NA 9 NA NA NA 9.5 13.7 12.9 8 15.1

Litter fall accumulation in forested lands seems to have also delivered organic P in Roberson
Creek. Osborne and Kovacic (1993) reported that during the winter dormant season, due to
continuous deposition of leaves, the level of P reaches saturation stage in forested land and
eventually leaks P. A separate field measurement of P concentration with regard to litter fall
accumulation in Roberson Creek watershed was not conducted in this study. However, an
assessment of P in this regard was undertaken by using a watershed model, Soil and Water
Assessment Tool, Version 2000. The results of the model are explained in the following sections.

2.2.2 Urban lands

Human activities in urban areas seem to be a major source of TP to Roberson Creek. Frequent
dish and car washing soaps and detergents that contain P could be a source of TP to the creek,
possibly via runoff and/or sewer leakage. The statewide phosphate detergent ban in 1988 may
have minimized some (but not all) of these sources. In North America and Europe, domestic
sewage produced by 1 person each year contains about 0.8 kg of P
(http://www.glencoe.com/sec/science/biology/ bacc / teacher_resources/pdfs/ext-inq.pdf).

Fertilizer applications to lawns are also a major source of TP in Roberson Creek. In 2001,
fertilizers used for lawns were 18-24-10 (N-P-K) and 10-10-10. The fertilizers were applied four
times in a year - two applications in March/April and remaining two in September/October. The
fertilizers were applied to lawns at the rate of 50 lbs. per 12,000 square feet. In a study conducted
in Lake Wingra and Lake Mendota, Madison, Wisconsin, the combined contribution of P within
the basins from lawns and streets was estimated to be 80%, with lawns contributing more than the
street (Waschbusch et al. 1995).

Roberson (Robeson) Creek TMDL Final Report

Overall, the combined effects of above point sources and non-point sources are estimated to be
0.26 mg/l of TP in a year-round average at the ambient station, RC8 (Figure 2.1). The station is
located about 1.8 mile upstream from the cove.

3 Modeling Approach
3.1 Receiving Water Model
3.1.1 Model Framework

The empirical eutrophication modeling package, BATHTUB v. 5.4, was employed to model the
effect of nutrient loading on water quality in the Roberson Creek Cove. An estimation of
tributary loadings for input into BATHTUB was determined using an associated model, FLUX v.
5.1.

BATHTUB applies nutrient balance and eutrophication response models to lakes and reservoirs
(including partial reservoirs and embayments) (Walker 1996). The program performs steady-
state water and nutrient balance calculations accounting for advective and diffusive transport and
nutrient sedimentation. Eutrophication related state variables are predicted from empirical
relationships developed and tested from assessment of US Army Corps of Engineers’ reservoir
data (Walker 1983). Inputs and outputs are expressed in probabilistic terms (mean and CV or
coefficient of variation) to account for limitations in data and model errors. Output CVs are
based on first-order error analysis.

Mass balances are computed at steady state over an appropriate averaging period. The averaging
period is typically 1 year for reservoirs with long residence times or seasonal (e.g. May-
September) for reservoirs with relatively short residence times. Day-to-day changes in load or
eutrophication parameters cannot be represented in the model. Therefore, short-term responses
and effects cannot be explicitly evaluated.

Several options are available within BATHTUB for modeling nutrient sedimentation, chl a, and
transparency. They include first and second order models of N and P sedimentation. Also, there
are 5 chl a models to choose from with variables including N, P, turbidity and flushing rate.
Roberson (Robeson) Creek TMDL Final Report

The model has been successfully applied in several management efforts in N.C. (Butcher et al.
1995, NCDEHNR 1992; Research Triangle Institute 1998) and throughout the U.S. (Kennedy
1995, Illinois Environmental Protection Agency 2002). BATHTUB has been cited as an effective
tool for water quality assessment, particularly where data are limited (Ernst et al. 1994).

FLUX is used to estimate tributary nutrient loading for input into BATHTUB from grab sample
concentrations and continuous flow data. The program derives flow weighted nutrient
concentrations from tributary sample data and continuous flow data over a specified averaging
period. Flow-weighted concentration is a ratio of the constituent load to the mean discharge.
Available loading calculations methods include direct load averaging, ratio estimates, and
regression methods.

Data for the period April 1 to October 31, 2001, an extended algal growing season, was used to
calibrate the BATHTUB model. A verification exercise was carried out using data from 2002 to
evaluate model performance.

3.1.2 Model Setup
3.1.2.1 Segment Morphometry

The Roberson Creek Cove was modeled in BATHTUB as a single reservoir embayment (spatially
averaged). Based on a comparison of data from RC10 and RC11, the two cove sites, this
configuration is appropriate because spatial variations in nutrients and chl a are relatively
unimportant. Longitudinal dispersion is not considered with this configuration. The cove length
(~1.75 km) and surface area (~0.13 km2) were approximated using georeferenced color infrared
photography (DOQQ; Figure 1.3) and standard GIS spatial measurement tools (ArcView 3.3).
The mean depth was 4.5 m and 3.2 m during 2001 and 2002, respectively. Mean depth of the
mixed layer was estimated using a multivariate regression equation provided by Walker (1996).

The major external inflow to the cove is Roberson Creek. Smaller inflows downstream of RC8 on
Roberson Creek are not monitored (or gaged) and must be accounted for indirectly by adjusting
Roberson (Robeson) Creek TMDL Final Report

loads and flows at RC8 upwards. The drainage divide at RC8 was manually delineated using
Arcview Spatial Analyst with the aid of a USGS topographic map.

The confluence of the Roberson Creek and the Haw River Arm of Jordan Lake is modeled as a
simple outflow boundary with no diffusive exchange. Outflow is predicted using water balance
calculations. The outflow assumption is based primarily on two factors: (1) the lack of hydraulic
flow data for diffusive exchange with the Haw River and (2) the lake elevations (and therefore
volume) at the Jordan Dam during 2001 decreased steadily between April and October supporting
the notion that flows did not back up into the cove. During 2002, the elevation at the Jordan Dam
decreased until September when it increased by about 2 meters from September through the end
of October. However, a hydrodynamic model of Jordan Lake indicated that net water movement
in the Haw River arm occurs overwhelmingly in the southward direction (Tetra Tech 2002).
Therefore, if any exchange does occur, it is likely limited to infrequent, isolated occurrences and
considered insignificant to the overall eutrophication response of the Roberson Creek Cove.

3.1.2.2 Climate Input and Atmospheric Loads

Precipitation data (2001 – 2002) from the Siler City Airport in Chatham County was supplied by
the State Climate Office of North Carolina. Located to the west of the cove, the Siler City station
was chosen due to its proximity to the Tick Creek stream over a station at Chapel Hill to the
north.

Pan evaporation data from Chapel Hill (Chapel Hill 2W) was provided by the National Climatic
Data Center in Asheville, NC. A pan coefficient of 0.71 was applied to calculate evaporation in
the cove (Yonts et. al 1973).

BATHTUB also requires atmospheric loading of nutrients. Data for wet and dry deposition of
TN was taken from U.S. EPA (2001; Candor station-CND125). Since data for 2002 was not
available, values from 2001 were also used in the 2002 verification exercise. Deposition of TP
was taken from Dodds et al. (1992).

Roberson (Robeson) Creek TMDL Final Report

3.1.2.3 In-Lake Concentrations

Monitoring data from the ambient station in the Roberson Creek Cove and data collected during
the TMDL study were summarized for input into BATHTUB. The model requires inputs of
growing season mean and CVmean for TN, TP, organic N, secchi depth, and chl a.
Orthophosphorus data were not available. For summary purposes, data below detection limit was
converted to one half of the limit value. Data from RC10 and RC11 were pooled (averaged
across stations on a given date). All values are based on surface grab samples since water column
profile data were not available for nutrients and chl a.

3.1.2.4 Tributary Loading Estimates

Daily Flow Estimates

FLUX requires daily mean flows for the selected period of interest. Roberson Creek is not gaged,
therefore flow data from a nearby station with a continuous flow record was adapted for use. In
selecting an appropriate gage, factors of proximity, drainage area characteristics, and location
within the same hydrologic area are important. Daily mean flow for Roberson Creek is estimated
based on constant runoff per square mile of the selected gage, adjusted for water withdrawals and
discharges.

Two candidate gages were considered: Rocky River at SR1300 (USGS 0210166029) and Tick
Creek (USGS 02101800). The drainage areas for the Rocky River and Tick Creek gages are 7.4
and 15.5 square miles, respectively. Both Chatham County sites are located in the same low flow
hydrologic area (HA7) as the Roberson Creek watershed (Giese and Mason 1993). Low flow
hydrologic areas are regions with relatively uniform low-flow characteristics. In the Piedmont,
underlying rock type is the most important factor influencing the delineations. The watersheds of
the Rocky River and Tick Creek gages are similar to Roberson Creek: heavily forested with
relatively small percentages of urban development.

Daily flows for Roberson Creek were estimated by multiplying flow at the candidate gage by the
ratio of the drainage areas (e.g., RC8 drainage area divided by Tick Creek drainage area). The
resulting flow was further adjusted for Pittsboro’s wastewater treatment plant discharge by adding
Roberson (Robeson) Creek TMDL Final Report

the flow to the estimated Roberson Creek flow (at RC8). A comparison of 2001 flow (April –
October) for the two gages with instantaneous flow from Roberson Creek site RC8 is shown in
Figure 3.1.

The daily flows estimated from the Tick Creek gage were chosen for further use in modeling. It
captured the storm flows better than the Rocky River gage and tracks the pattern of instantaneous
flow measurements reasonably well. Note that flow is underestimated in part of late summer and
fall. However, most of these flows are below 5 cfs so the difference is not expected to have a
large effect on loading estimates.

Figure 3.1. Comparison of estimated Roberson Creek stream flow at RC8 using Tick Creek and
Rocky River gages (adjusted for wastewater treatment plant flow) with instantaneous flow
data collected at RC8.

2001 Estimated Roberson Creek Daily Mean Flows (RC8)
0.001
0.01
0.1
1
10
04
/
0
1
/
0
1
04
/
1
5
/
0
1
04
/
2
9
/
0
1
05
/
1
3
/
0
1
05
/
2
7
/
0
1
06
/
1
0
/
0
1
06
/
2
4
/
0
1
07
/
0
8
/
0
1
07
/
2
2
/
0
1
08
/
0
5
/
0
1
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/
1
9
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0
1
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/
0
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/
0
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/
1
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/
0
1
09
/
3
0
/
0
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/
1
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/
0
1
10
/
2
8
/
0
1
cu
b
i
c

m
/
s
Roberson Instantaneous Sample Flow
Tick Crk DA Ratio + wwtp flow
Rocky River DA Ratio plus wwtp
Roberson (Robeson) Creek TMDL Final Report

Selection of Loading Calculation Method

There are many different approaches that can be used to estimate nutrient loads from observed
concentration and flow data. The true value of load can only be determined with continuous flow
and concentration records. Several choices are available within FLUX for load calculations
including direct load averaging (Method 1), ratio estimates (Methods 2 and 3), and regression
methods (Methods 4-6). Loading estimates are generally chosen based upon minimum bias and
minimum variance. Unrepresentative sampling or use of an inappropriate calculation method
contributes to bias, representing the difference between the estimate and the true value. Method
selection is often based primarily upon minimum variance given representative sampling and
reasonably independent residuals (flow, date, and autocorrelation). Optional stratification of the
data into subgroups based on flow, date, and/or season may increase accuracy and precision of
loading estimates in some cases.

Load Determination for 2001

In smaller, flashy streams like Roberson Creek, variance and extremes of instantaneous sample
flows will be higher than those of daily mean flows. In order to reduce bias, daily mean flows
were substituted for instantaneous sample flows (Walker 1996).

The data were stratified into two subgroups based on flow. Although the averaging period was
generally dry, there were a small number of samples collected following storms (Figure 3.2).
Data limitations allowed only 3 samples (model minimum) in the highest flow strata. Following
data stratification, loading estimates using methods 1 through 4 tended to converge and the CV
values were reduced. This limited variation among calculation methods is desirable and indicates
robustness. Estimated mass loading to this site among all six calculation methods ranged from
489 to 618 kg of P. Selection was based on the lowest CV value and the lack of slope
significance for residuals graphed versus date and flow. Method 3 was chosen in all cases.

Method 3 in the FLUX model is a modified ratio estimator based on Beale (1962), which
calculates load as the flow-weighted average concentration times the mean flow over the average
period with a statistical correction for bias (Table 3.1). This ratio method performs best when
flow and concentration are weakly related, although it adjusts for potential bias when there is a
stronger relationship. A plot of TP concentrations with flow generally confirms this type of
Roberson (Robeson) Creek TMDL Final Report

relationship (Figure 3.3). At the highest flows, concentration decreased during the period of
interest. The pattern was similar for TN and inorganic N. Ratio methods, in general, tend to be
more robust than other approaches with respect to bias from constituent characteristics (Preston et
al. 1989).
Roberson (Robeson) Creek TMDL Final Report

Table 3.1 FLUX equations used for calculation of tributary loads to Roberson Creek (from
Walker 1996).

Roberson (Robeson) Creek TMDL Final Report

Figure 3.2. Plot of daily flow record (April – October 2001) and dates of sample collection (red
squares) for RC8 on Roberson Creek. The symbols indicate the daily flows on the dates of
sample collection. Flow units are hm3/yr (= cfs * 0.893).

Roberson (Robeson) Creek TMDL Final Report

Figure 3.3. Plot of sample flow (hm3/yr) versus total phosphorus concentration (mg/m3) during
the period April through October, 2001 at RC8.

Load Determination for 2002

For summer 2002, the data were limited (8 sampling dates, April – August) and storm flows,
primarily during October, were not sampled (Figure 3.4). Therefore, a low percentage of the flow
volume was sampled. Walker (1996) recommends using calculation method 2 or 3 when load
estimates must be generated from limited data and weakly representative sampling. The data
were not stratified into subgroups and flow substitution was not used. The choice between
method 2 or 3 was decided based upon the lowest CV value. Method 2 was chosen in all cases.
This method is similar to method 3 used for 2001 and can be considered a ratio estimate (Table
3.1).
Roberson (Robeson) Creek TMDL Final Report

Figure 3.4. Plot of daily flow record (April – October 2002) and dates of sample collection (red
squares). The symbols indicate the daily flows on the dates of sample collection. Flow
units are hm3/yr.

Loading Results

Data collected at the most downstream tributary station, RC8, was used to calculate loads and
flow-weighted concentrations using FLUX. The watershed area above RC8 is approximately
24.6 square miles (~86% of the Roberson Creek watershed). Loading estimates generated with
FLUX were adjusted upward slightly to account for the additional drainage area downstream of
RC8 assuming a constant load per unit area. Accordingly, the summer loading estimate to the
cove for TP loading in 2001 was 597 kg with a standard error of 101 kg. This load is computed
by multiplying the adjusted flow volume during the period (6.9 hm3/yr*0.586) by the flow-
Roberson (Robeson) Creek TMDL Final Report

weighted concentration derived using method 3. Table 3.2 presents flow-weighted concentrations
for TP, TN and inorganic N required for input into BATHTUB.

Since orthophosphorus data were not available, input for BATHTUB was assumed to be 70% of
TP. Although higher than the proportion used for the Jordan Lake Nutrient Response Model
(55%; Tetra Tech 2002), this conservative approach is supported by the dominant role of the
Pittsboro wastewater treatment plant. Phosphorus in wastewater (raw to treated) is 60 to 70%
inorganic on average (Thomann and Mueller 1987).

Table 3.2. Estimated summer flow-weighted concentrations for the Roberson Creek Cove using
adjusted FLUX results (April through October).

2001
Concentration
(mg/L) CVmean*
Total
Phosphorus 0.148 0.170
Total Nitrogen 1.950 0.153
Inorganic
Nitrogen 1.426 0.226

2002
Concentration
(mg/L) CVmean
Total
Phosphorus 0.166 0.165
Total Nitrogen 2.369 0.147
Inorganic
Nitrogen 1.915 0.182
* CVmean = standard error of the mean divided by the mean.

3.1.3 BATHTUB Calibration

Data for the period April 1 to October 31, 2001 (a dry year) was used to calibrate the BATHTUB
model. Following specification of data inputs, water balances were checked for conservation of
mass. Calculated nutrient turnover ratios (length of averaging period/mass residence time) that
exceed 2.0 support the use of a seasonal averaging period, the period over which water and mass
Roberson (Robeson) Creek TMDL Final Report

balance calculations are performed. For 2001, turnover ratios for the uncalibrated model were
11.0 and 10.3 for TP and TN, respectively. Hydraulic residence time was approximately 31 days
during 2001.

Application of BATHTUB proceeds with selection and calibration of submodels for nutrient
sedimentation (N and P) and empirical eutrophication response for chl a. Selection of a submodel
for diffusion was not necessary for this application since the cove is considered as a single
segment.

Several t-statistics calculated from observed and estimated data are used to select and calibrate
submodels. Two statistics supplied by the model, T2 and T3, aid in testing model applicability.
T2 is based on error typical of model development data set. T3 is based on observed and
predicted error, taking into consideration model inputs and inherent model error. The statistics
indicate whether the means differ significantly at the 95% confidence level. If their absolute
values exceed 2, the model may not be appropriate. The T1 statistic can be used to determine
whether additional calibration is desirable. In cases where predicted and observed values differ
significantly, calibration coefficients can be applied to account for the site-specific application of
the model. Calibration to account for model error is often appropriate. However, Walker (1996)
recommends a conservative approach to calibration since differences can result from factors such
as measurement error and random data input errors.

For P and N sedimentation, the initial test of model applicability excluded first order models. In
the case of P, a second order decay rate function (model 2) was chosen for its superior fit using
T2 and T3 error statistics. The Bachman (1980) model based on volumetric load was selected for
N sedimentation. T1 values for both models indicated that additional calibration was not
necessary.

Chlorophyll model selection and calibration proceeds similar to nutrients described above. The
available chl a models in generalized form are shown in Table 3.3. Following exclusion of
models 1, 2 and 5 based on T2 and T3 error statistics, model 3 and 4 were evaluated further.
Secchi depth in the cove indicates that irradiance (light) is not an insignificant control on algal
productivity. Since a term for light is not included in the two candidate models, predicted chl a
may be overestimated. Model 4 underestimated chl a concentrations, which appeared
counterintuitive. Therefore, Model 3 was selected (Equation 3.1).
Roberson (Robeson) Creek TMDL Final Report

chl a = CB*0.2*(Xpn 1.25)----------------------------(3.1)
Xpn = [P-2 + ((N-1 50)/12) -2] -0.5

Chlorophyll a concentration is in units of mg/m3 (or µg/L) and the composite nutrient (P and N)
concentration in mg/m3 (Xpn) is based on TN and TP (see Walker 1996). A calibration factor
(CB) of 0.83 was applied to the model to account for a minor overestimation. The empirical
models available within BATHTUB are generalizations about reservoir response. Unique
features of a particular reservoir often requires calibration in this fashion to match observed
reservoir conditions. Such an adjustment is necessary and appropriate if done in a conservative
manner as recommended by Walker (1996).

To some extent, the calibration factor incorporates the depressive effects of light limitation on
algal growth. The utility of this factor is limited, however, because the model is not linear.
Finally, since organic N is calculated using chl a, a calibration factor of 0.83 was applied to this
constituent as well. Final results of the calibrated model are presented in Figure 3.5.

Table 3.3. Chlorophyll a models within BATHTUB described according to limiting factors.

Model Limiting Factors
1 P, N. light, flushing
2 P, light, flushing
3 P, N
4 P (linear)
5 P (exponential)

Roberson (Robeson) Creek TMDL Final Report

Figure 3.5. BATHTUB calibration for Roberson Creek Cove (April – October 2001). Values
plotted are observed and estimated means +/- one standard error.

3.1.4 BATHTUB Verification

Data from 2002 were used to test the accuracy and predictive capability of the calibrated model.
The model was run using 2002 input (climate, lake concentrations, and tributary loading) with the
same submodels and calibration coefficients derived during the calibration process.

Results for the period April through October indicate over-prediction of nutrients, particularly
nitrogen (Figure 3.6). Since nutrient samples were not collected during October 2002, a potential
for bias in the loading estimate was suspected. The area experienced a drought during the
summer of 2002 and the majority of precipitation occurred during October. The calculated mean
flow for 2001 and 2002 (April – October) was 0.17 cms (CVmean =.20) and 0.18 cms (CVmean
=.56), respectively.
Roberson (Robeson) Creek TMDL Final Report

Since nutrient samples to calculate loads were not collected during October, a potential for bias in
the loading estimate was suspected so the model was run without October input. Results indicate
improved performance for nutrients (Figure 3.7).

The growing season average for chl a predicted by the model is underestimated but within
reasonable performance ranges (using t statistics; Figure 3.7). A reduction in abiotic turbidity
during the low flow drought period could have contributed to an underestimation of chl a.
Although a factor was applied to the calibrated model to partially account for the effects of light
limitation, the model is limited when there are large deviations from the non-algal turbidity
conditions experienced during the calibration period. Based on these results, the verification
indicates the model adequately describes the observed behavior and demonstrates acceptable
predictive capacity for below average hydrologic conditions.

Roberson (Robeson) Creek TMDL Final Report

Figure 3.6. BATHTUB verification for Roberson Creek Cove using data inputs from April –
October 2002. Values plotted are observed and estimated means +/- one standard error.

Roberson (Robeson) Creek TMDL Final Report

Figure 3.7. BATHTUB verification for Roberson Creek Cove using data inputs from April –
September 2002. Values plotted are observed and estimated means +/- one standard error.

Roberson (Robeson) Creek TMDL Final Report

3.2 Watershed Loading Model

A physically-based watershed model, the Soil and Water Assessment Tool (SWAT), Version
2000, was used to assess the impact of point source and non-point source on TP in Roberson
Creek watershed with varying land use and management conditions for 2001. The model was
developed by Dr. Jeff Arnold for the USDA Agriculture Research Service. It is a continuous time
model and enables the user to study long term impacts of nutrients. The model has been
interfaced with ArcView GIS in a software package known as AVSWAT-2000 (Luzio, et al.
2002). In this study, the software was used for watershed delineation, hydrological and
agriculture management inputs, and model calibration.

The watershed model computes surface runoff volume using a modification of the SCS curve
number method and peak runoff rate predictions using a modification of the rational method. The
model routes flow through the channel using a variable storage coefficient method.

The watershed model monitors six different pools of P in soils. Three pools are inorganic forms
of P while the other three pools are organic forms of P. Fresh organic P is associated with crop
residue and microbial bio-mass while the active and stable organic P pools are associated with
soil humus. Soil inorganic P is divided into solution, active, and stable pools. Total phosphorus
(TP) is the sum of organic P and inorganic P.

The model allows nutrient levels to be input as concentrations. However, it performs all
calculations on a mass basis. To convert a concentration to a mass, the concentration is
multiplied by a bulk density and the depth of the layer and divided by 100.

Nutrient transformations in the stream are controlled by the in-stream water quality component of
the model. The in-stream kinetics used in SWAT for nutrient routing are adapted from the
QUAL2E model. The model tracks nutrients dissolved in the stream and nutrients adsorbed to
the sediment. Dissolved nutrients are transported with the water while those sorbed to sediments
are allowed to be deposited with the sediment on the bed of the channel. A detailed process of P
is posted at http://ftp.brc.tamus.edu/pubs/swat/doc/ swat2000theory.pdf.

Roberson (Robeson) Creek TMDL Final Report

3.2.1 Model Setup

Roberson Creek watershed was delineated by using the ArcView interface SWAT model,
AVSWAT. The model utilizes the Reach file 3(RF3) stream coverage and Digital Elevation
Model (DEM) data to delineate the watershed. The model assigns a hydrologic unit code to each
land use type in each sub-watershed to estimate hydrologic responses and nutrient pools. The
estimated hydrologic responses and nutrients pools are then routed towards watershed outlets.

A total of six sub-watersheds were delineated for this study (Figure 1.5). Sub-watershed 1
consisted of the urban area of Pittsboro and the Pittsboro WWTP. Sub-watersheds 2 and 4,
respectively, represented Turkey Creek and Camp Creek. Both creeks collected nutrients from
wastewater spray fields. The nutrient loads collected from the sub-watersheds 1, 2 and 4 were
routed through the sub-watersheds 3, 5, and 6. Sub-watershed 6 contains the Roberson Creek
cove off Jordan Lake.

Since the watershed model is not designed for cove conditions, the application of the model was
limited up to the sub-watershed 5. The ambient station, RC8, was located at the mouth of sub-
watershed 5 and therefore, is considered for the model calibration as well as for TMDL
allocation.

3.2.1.1 Model Inputs

The model, SWAT-2000, was set up with major input parameters: weather, agriculture
management, and point source discharge. The weather data collected by the nearby weather
station located at the Siler City Airport was acquired through the State Climate Office of North
Carolina. Rainfall and temperature data for the study year 2001 are presented in the Appendix.
The total rainfall during 2001 was 754 mm. The amount of rainfall was considerably less than the
long term mean annual rainfall, 1205 mm (Source: The State Climate Office of North Carolina).
Therefore, the study year 2001 was a dry year.

Soil parameters including bulk density, soil layer, available water, hydraulic conductivity, and
texture type were acquired by the U.S. STATSGO database for this study. There were three types
of soils in the watershed: Herndon (NC061), Goldston (NC064), and Wedowee (NC068).
Roberson (Robeson) Creek TMDL Final Report

Cultivation of hay was the major agricultural practice in the watershed. The common cultural
practices that were input into the model are explained in
2.2 above.

Pittsboro WWTP was the only point source that discharged effluent water to Roberson Creek.
The discharge rate and the concentration of TP are presented in Appendix XIII. The
summarization of the data is explained in
2.1 above.

3.2.2 Model Calibration

Flow and nutrient data measured at station RC 8 during 2001 was utilized to calibrate the model.
Because ground cover and infiltrability of land changes with season, the model was calibrated for
summer season (April-October) and winter season (November-March). The adjusted parameters
to calibrate the model with regards to the two seasons are presented in Table 3.4. The model
calibration results follow.

3.2.2.1 Flow

Calibration of the model with regards to flow is essential, because the flow is the main carrier of
TP. Time series of the simulated and observed flow for the year 2001 are presented in Figure 3.8.
On average, the model predicted a flow rate slightly less than the observed flow rate (Table 3.5).
However the difference between the estimated and observed flow rate was not significantly
different (P > 0.05). Also, the correlation coefficient between the observed and the simulated
flow rate was 0.92. The strong correlation suggests that the model simulated the flow rates
closely with the observed rates.

Roberson (Robeson) Creek TMDL Final Report

Figure 3.8. Comparison of observed flow and simulated flow at the ambient station RC 8 for
2001.

0.00100
0.01000
0.10000
1.00000
10.00000
100.00000
01
0
1
2
0
0
1
01
1
9
2
0
0
1
02
0
6
2
0
0
1
02
2
4
2
0
0
1
03
1
4
2
0
0
1
04
0
1
2
0
0
1
04
1
9
2
0
0
1
05
0
7
2
0
0
1
05
2
5
2
0
0
1
06
1
2
2
0
0
1
06
3
0
2
0
0
1
07
1
8
2
0
0
1
08
0
5
2
0
0
1
08
2
3
2
0
0
1
09
1
0
2
0
0
1
09
2
8
2
0
0
1
10
1
6
2
0
0
1
11
0
3
2
0
0
1
11
2
1
2
0
0
1
12
0
9
2
0
0
1
12
2
7
2
0
0
1
Date
Fl
o
w

(
c
u
m
/
s
)
Estimated Observed
Roberson (Robeson) Creek TMDL Final Report

Table 3.4. Adjusted parameters for the model calibration.

Season/Land Types Channel
Hydraulic
Conductivity
(k in mm/hr)
Manning’s n Curve
Number
(CN)
Support Practice
Factor
(USLE-P)
1. Summer
Urban
Forest
Pasture/Hay Land (WS 1,3,5,6)
Pasture/Hay Land (WS 2,4)

20.00

0.014
82
55
61
74

1.00
0.60
0.60
0.80
2. Winter
Urban
Forest
Pasture/Hay Land (WS 1,3,5,6)
Pasture/Hay Land (WS 2,4)
0.00 0.10
82
60
69
79

0.10
0.35
0.15
0.15

Table 3.5. Estimation of mean and standard error for the flow rates.

Seasons Observed (cum/s) Estimated (cum/s)
Summer 0.40± 0.30 0.34 ± 0.23
Winter 1.40 ± 0.80 1.10 ± 0.42

3.2.2.2 Total Phosphorus

Flow measurement at the ambient station, RC8, was not continuous; the measurement was taken
only 2-4 times in a month. The gap between the measurements can potentially result in high
variance when estimating daily average TP loads (Preston et al. 1989; Hodgkins 2001). Daily
load was estimated by multiplying TP concentration with respective flow and conversion factor
(Equation 3.2) in this study.

Load (kg/day) = flow (cum/s) * concentration (mg/l) * 86.4 --------------------(3.2)

In order to reduce the variance, daily mean flow and daily TP measurement are required.
There are many different approaches that can be used to estimate daily TP loads from non-
continuous flow data. Some of the approaches are explained above (
3.1.2.4). For the watershed
Roberson (Robeson) Creek TMDL Final Report

model, a regression method based on load and flow was used. The procedure adopted is as
follows: The measured TP concentration was first converted to TP load by using the above
equation 3.2. The estimated load was then correlated with measured flow. The correlation is
expressed by the following regression equations 3.3 and 3.4

Summer:
TP (kg) = 1.79 + 7.45 * Flow (cum/s) -------------------------(3.3)
R-Square = 0.96

Winter:
TP (kg) = 0.28 + 20.83 * Flow (cum/s)--------------------------(3.4)
R-Square = 0.90

Because the daily mean flow as estimated by the watershed model closely followed with the
measured flows (Table 3.3 and Figure 3.8), the estimated daily mean flow was utilized to estimate
daily mean TP load by using the above equations 3.2 and 3.3 for summer and winter seasons
respectively. The estimated TP loads using the regressing equations were then compared with the
estimated load using the watershed model. The difference between the two estimations was not
significant when they were compared with respect to estimated mean load and total load for the
both seasons (Table 3.6 and Figure 3.9). Also the daily summer load of TP as estimated by the
SWAT model was within 1 standard error of the estimation by the FLUX model (Table 3.6).

Table 3.6. Estimation of mean and standard error for TP (kg/day) at the station RC 8.

Seasons Load Regression
Method
SWAT Model FLUX Ratio Method
Summer 3.19 ± 0.31 3.05 ± 0.4 2.40 ± 0.41
Winter 12.3 ± 1.97 11.97 ± 3.15 --

Roberson (Robeson) Creek TMDL Final Report

3.2.3 Model Output

The watershed model indicated that the discharge rate of water at the ambient station, RC8, was
substantially higher during winter than summer (Figure 3.9). In total, winter TP load was 63%
more than the summer TP load.

Figure 3.9. Total load of total phosphorus as estimated by the load regression method and the
SWAT model for the study year 2001.

Non-point sources were greater contributors of TP during the winter season (Table 3.7). Urban
areas contributed an estimated 814 kg (45%) of TP in 2001. Also, it appears that litter fall in the
forested land contributed about 344 kg of TP (19%) and pasture/hay lands contributed about 253
kg (14%). Twenty one percent (21%) of the pasture/hay lands contribution was derived from
subwatersheds 2 and 4, where the wastewater spray fields were located.

683.07
1857.13
652.6
1808.34
0
200
400
600
800
1000
1200
1400
1600
1800
2000
Summer Winter
Seasons
TP

(
k
g
)
Regression TP Model TP
Roberson (Robeson) Creek TMDL Final Report

Contributions from forested lands and pasture lands were almost negligible during summer 2001
(Table 3.7). It could be due to low flow, less litter fall, and high infiltration rates. During
summer, infiltrability of lands remains high due to low soil moisture condition. The soluble P
would then most likely to be leached down to ground water. Recharge of P from ground water to
the creek is assumed to be negligible in this study.

Pittsboro WWTP and wet-weather load from urban lands were the two major sources of TP
during summer, with the WWTP being the largest source of TP (77%). The WWTP contributed
about 503 kg and 398 kg of TP during summer and winter respectively. The plant contribution
was about 26% more during summer. In a contrast, the urban contribution was about 80% less
during summer. Urban sources may include stormwater runoff and leaking sewer lines.

Table 3.7. Total phosphorus loads (kg) delivered to station RC 8 during 2001.

Source Types Summer % Winter %
1. Non-point source
Urban
Forest
Pasture/Hay Land
2. Point source
WWTP

Total

150
_
_

503

653

23

77

100

814
344
253

398

1808

45
19
14

22

100

Roberson (Robeson) Creek TMDL Final Report

4 Allocation
4.1 Total Maximum Daily Load (TMDL)
A Total Maximum Daily Load is the maximum amount of a pollutant that a water body can
receive and still meet water quality standards, partitioned among point and nonpoint sources. A
TMDL is comprised of the sum of wasteload allocations (WLA) for point sources, load
allocations (LA) for nonpoint sources, and a margin of safety, expressed by the equation:












The objectives of the TMDL are to estimate allowable pollutant loads, and to allocate them
among the general pollutant sources in the watershed. 40 CFR §130.2 (i) states that TMDLs can
be expressed in terms of mass per time (e.g. pounds per day), toxicity, or other appropriate
measures. This TMDL will be expressed in terms of % TP load reduction and allowable load in
kilograms, representing the maximum load the water body can assimilate and maintain the water
quality criterion for chl a.

The calibrated model was applied to predict the impacts of alternative P loading scenarios. The
target is to have no more than 10% of the samples exceed a chl a concentration of 40 µg/L.
Model results indicate that a 50% reduction in TP load based on 2001 conditions is needed to
meet the chl a standard without an added margin of safety (Figure 14). However, due to
uncertainty in data and the model, a margin of safety based in probabilities was incorporated into
the TMDL.

The model predicts a mean growing season chl a of 21.9 µg/L when the frequency of
concentrations above 40 µg/L is 10% (Figure 4.1). The associated 80% confidence interval
around the mean, 14.0 µg/L to 34.3 µg/L, was calculated according to Walker (1996) using the
calibrated model’s value of CVmean (0.33) for chl a. Critical values of the t distribution were
obtained from statistical tables in Zar (1999). The measure of model uncertainty, CVmean,
incorporates model error based on seasonal variability and inherent model error.

Roberson (Robeson) Creek TMDL Final Report

The margin of safety for this TMDL is based on meeting the lower 80% confidence limit (14
µg/L). Accordingly, a reduction in TP load of 71% would be needed to provide “certainty” at the
80% confidence level, that the water quality standard will be met. This reduction scenario would
allow less than 3% exceedence of the 40 µg/L chl a standard based on model results.

Figure 4.1. Load reduction scenarios for total phosphorus (TP) in the Roberson Creek Cove.
TMDL target standard is to have less than or equal to 10% of the samples above the
chlorophyll a standard of 40 µg/L. The margin of safety (MOS) is based on an 80%
confidence limit of model predictions.

Roberson (Robeson) Creek TMDL Final Report

4.2 Critical Conditions

The allowable TP load to the Roberson Creek Cove is based on an identified critical condition: a
dry hydrologic period during the algal growing season. During the averaging period of 2001
(April – October), the average mean daily flow was 41% of the historical 43-year average based
on flow at the Tick Creek USGS gage. This dry year is considered to be the critical hydrologic
condition for nutrient enrichment since residence time and nutrient retention is maximized. With
particularly severe drought conditions during April through September, 2002 was also a dry year.
However, sufficient data was not available to use 2002 for the reduction target. In addition, a
drought of such severity represents an extreme condition.

Nutrient loading will vary year-to-year based on changes in flow regime. Nutrient loading data
from wet years was not available for this modeling effort. However, nutrient loads associated
with higher flow years will be flushed through the cove more rapidly resulting in a shorter
residence time. The higher flows will also be accompanied by an increase in algal light limitation
due to abiotic turbidity (Reynolds 1984).

4.3 Seasonal Variation

Chlorophyll a concentrations in the Roberson Creek cove tend to be highest during the summer
growing season. Blooms can occur during other times of the year to a much lesser extent (Figure
1.6). Conditions of lower water temperature, lower irradiance, and higher flow generally
suppress algal growth during winter and early spring. Higher nutrient loads during the colder
weather months tend to be flushed through the system rapidly, making nutrients unavailable for
algal uptake. Moreover, lower solar radiation and a more turbid water column during these
periods will also suppress algal productivity. Thus, this TMDL focuses on nutrient loading and
algal response during an extended growing season of April through October only. Basing the
TMDL on this warm weather period will protect Roberson Creek during the cold weather period
(November – March).

Seasonal variation during the averaging period in nutrient load and response is captured within
the models used for this TMDL. In BATHTUB, it is incorporated in terms of seasonal averages
Roberson (Robeson) Creek TMDL Final Report

for summer and associated error terms. For SWAT, summer and winter conditions during 2001
are modeled to understand nutrient loading over an annual period.

4.4 Model Uncertainty and Margin of Safety

The margin of safety is an additional factor of the TMDL that accounts for uncertainty in the
relationship between pollutant loads and receiving water quality. This margin of safety can be
provided implicitly through conservative analytical assumptions and/or explicitly by reserving a
portion of the load capacity.

For Roberson Creek, an explicit margin of safety has been applied to the water quality criterion.
It is based on meeting the lower 80% confidence limit of the predicted mean chl a concentration
at the 10% exceedence level. The BATHTUB model calculates a measure of error based on
seasonal variability and inherent model error (CVmean). The confidence intervals were calculated
using values of CVmean for chl a according to Walker (1996; p.1-9) using statistical tables in Zar
(1999).

In the receiving water model, uncertainty in loads is incorporated into the analyses by including a
CV in the model input. The loading values and error are calculated within FLUX. The lack of
agreement between modeled, both FLUX and SWAT, and estimated P concentrations could be
due in part to the uncertainty associated with calculating loads from non-continuous data (Preston
et al. 1989). In addition, FLUX uses statistical techniques to estimate loadings rather than
process-based formulations used in SWAT.

The inability to accurately predict specific observed P loading within SWAT can be attributed to
model error, lack of sufficient information in source assessment, gaps in our scientific knowledge,
natural variability in P concentrations, field and laboratory measurement error, and lack of current
site specific model input parameters. The watershed model, SWAT, selected to guide initial
decision making, is not adept at characterizing prediction uncertainty. Because of the lack of
certain site specific information, professional best judgment and literature values were used to
calculate the P loading from the various land uses. Therefore, the model results should be
interpreted in light of the model limitations and prediction uncertainty.

Roberson (Robeson) Creek TMDL Final Report

4.5 Waste Load Allocation

Pittsboro WWTP was the only point source in Roberson Creek watershed during the study period.
The plant contributed about 503 kg of TP during summer (Table 3.6). As per the discussion in

4.1 above, reduction of TP required to meet the chl a standard at the Roberson Creek Cove with a
margin of safety is 71%. Therefore, reductions of TP required from the WWTP were estimated to
be 357 kg for summer.

4.6 Load Allocation

Non-point sources that contributed TP in the Roberson Creek watershed were urban lands,
forested lands, and pasture/hay lands on an annual basis. There are no permitted stormwater
sources (MS4) in this watershed. Urban lands were the only non-point sources that contributed
153 kg of TP during summer season (Table 3.7). Reduction required from the urban lands to meet
the chl a in the cove was, therefore, 106 kg. Overall, the reduction of TP required to meet the chl
a standard at the Roberson Creek cove was 464 kg during the summer season (April – October).

Table 4.1. Total mass daily load allocation of total phosphorus in kilograms (kg).

Source Types TMDL for
Summer
(April - October)
%
Reduction

1. Non-point source
Urban
Forest
Pasture/Hay lands

2. Point source
WWTP

Total

44
--
--

146

190

71
0
0

71

71

Roberson (Robeson) Creek TMDL Final Report

5 Implementation Plan

The TMDL analysis was performed using the best data available to specify the nutrient reductions
necessary to achieve water quality criteria: the chl a target in this lower portion of Roberson
Creek. The intent of meeting the criteria is to support the designated use classifications in the
watershed. The decision to focus on P was based on the assumption that P will ultimately control
growth in the cove and reductions in P will drive the cove to an increasingly P limited state (by
increasing the N:P ratio). As a practical matter, some reductions of N will likely accompany P
reductions. This is desirable because although N is not the primary limiting nutrient during most
of time, loading of N does contribute to algal growth in the cove. Furthermore, downstream
waters such as Jordan Lake may be affected by N contribution from this watershed. Therefore, an
increase in N loading is not be recommended.

The TMDL requires reductions from urban sources of P and Pittsboro’s wastewater treatment
plant. In addition to reductions form existing urban sources, future growth in urban land uses
within the watershed should be accompanied by nutrient control measures.

This TMDL targets an algal growing season due to timing of algal blooms and residence time in
the cove. The reductions will protect Roberson Creek and its intended uses during all times of the
year. Nonetheless, nutrient controls during winter are suggested for two reasons. First,
downstream waters (Jordan Lake) are affected by nutrients transported from this watershed.
Second, there may be some stored P within the watershed derived from the winter that may be
transported to the cove during summer.

A detailed implementation plan is not included in this TMDL. The involvement of local
governments and agencies will be needed in order to develop the implementation plan. During
2002, the NCSU Water Quality Group received a EPA Section 319 grant to perform a watershed
assessment of the Roberson Creek watershed. Part of the project will involve identification of
areas for targeting of best management practices (BMP) within the watershed. The Water Quality
Group will be developing general and site-specific implementation plans for Roberson Creek.

Roberson (Robeson) Creek TMDL Final Report

6 Stream Monitoring

Monitoring will continue on a monthly interval at the ambient monitoring site in the Roberson
Creek Cove. The continued monitoring of nutrient and chl a concentrations will allow for the
evaluation of progress towards the goal of achieving water quality standards and intended best
uses.

7 Future Efforts

Overall, the reduction of TP required to meet the chl a standard at the Roberson Creek cove was
464 kg during the summer season. Nutrient loading will vary year-to-year based on changes in
flow regime. The allowable TP load to the Roberson Creek Cove is based on an identified critical
condition for nutrient enrichment: a dry algal growing season. Dry hydrologic conditions in
Roberson Creek Cove would be expected to maximize residence time and nutrient retention,
thereby promoting algal growth (Wetzel 2001). Further monitoring and modeling may be
desirable in the future to confirm these assumptions. Future work may include an enhanced
characterization of the relationship between flow and nutrient concentrations across a range of
hydrologic conditions. Likewise, an analysis of eutrophication response during wetter years may
be useful.

8 Public Participation

A draft of the Roberson Creek TMDL was publicly noticed through various means, including
notification in the local newspaper, The Chatham Record, on June 19, 2003. DWQ electronically
distributed the draft TMDL and public comment information to known interested parties. The
TMDL was also available from the Division of Water Quality’s website at
http://h2o.enr.state.nc.us/tmdl/draft_TMDLs.htm during the comment period beginning June 19
and ending July 21.

A public meeting was held on July 15 at the Chatham County Agricultural Center Auditorium in
Pittsboro. At this meeting, staff presented the TMDL and answered questions. In addition to
Roberson (Robeson) Creek TMDL Final Report

DWQ staff, 14 people attended the meeting. Person attending represented environmental
advocacy groups (3), local government agencies (6), research univeristies (3), and private
landowners (2).

9 Further Information

Further information concerning North Carolina’s TMDL program can be found on the Internet at
the Division of Water Quality website: http://h2o.enr.state.nc.us/tmdl/.

Technical questions regarding this TMDL should be directed to the following members of the
DWQ Modeling/TMDL Unit: J. Todd Kennedy, Modeler ([e-mail]), Narayan
Rajbhandari, Modeler ([e-mail]), and Michelle Woolfolk, Supervisor
([e-mail]).
Roberson (Robeson) Creek TMDL Final Report

10 Responsiveness Summary

A draft of the Roberson Creek TMDL was publicly noticed through various means, including
notification in the local newspaper, The Chatham Record, on June 19, 2003. DWQ electronically
distributed the draft TMDL and public comment information to known interested parties. The
TMDL was also available from the Division of Water Quality’s website at
http://h2o.enr.state.nc.us/tmdl/draft_TMDLs.htm during the comment period beginning June 19
and ending July 21.

A public meeting was held on July 15 at the Chatham County Agricultural Center Auditorium in
Pittsboro. At this meeting, staff presented the TMDL and answered questions.

Four people submitted written comments concerning the proposed TMDL:

1. Keith Megginson
Chatham County Planning Director
June 12, 2003

2. Elaine Chiosso and Catherine Deininger
Haw River Assembly
July 21, 2003

3. David B. Hughes
Town Manager, Town of Pittsboro
July 23, 2003

4. Robert W. Slocum, Jr.
Executive Vice President, NC Forestry Association
July 25, 2003

Roberson (Robeson) Creek TMDL Final Report

Although comments from Mr. Hughes and Mr. Slocum were received after the official comment
period ended, responses have been provided.

1. Comments from Keith Megginson

Comment:
My comment is about page 18, section 2.2.2. In said section it gives P loadings for domestic
sewage and addresses dish washing as possibly increasing the level of P. I did not find that the
document addresses how this relates to P loadings in Roberson Creek, whether by failing septic
systems in the rural areas or increased loadings to Pittsboro WWTP.

Response:
The commenter is correct: this is an indirect load of P to the system. As a result of dish washing,
the P in some detergents may be transported to septic systems and/or the wastewater treatment
plant. Despite the intermediate fate (septic tank or WWTP), the P may ultimately be transported
from the watershed to the Roberson Creek Cove.

2. Comments from Haw River Assembly

Comment:
Any TMDL for Robeson Creek needs to account for additional future sources of non-point source
pollution due to growth. Pittsboro is on the brink of a significant amount of growth. If this
TMDL doesn’t include an allocation for growth, any development in Pittsboro could quickly
overwhelm the pollutant cap and prevent achievement for water quality standards for Robeson
Creek. Failure to meet water quality standards, technically, could cause a prohibition of all future
pollutant loads. Therefore, it is in the best interest of the state and local government to account
for anticipated growth.

Response:
The margin of safety within the TMDL acts to preserve a portion of the assimilative capacity. In
addition, the TMDL contains an implicit factor for growth as it pertains to the wasteload
allocation. Any future growth in waste flows to the plant will be limited by the summer
Roberson (Robeson) Creek TMDL Final Report

wasteload allocation. Nonpoint source controls should be implemented concomitant with future
growth of the town to prevent net increases in urban sources of P. Monitoring will continue in
the Roberson Creek Cove as this TMDL is implemented. If necessary, the TMDL will be
revisited if the waterbody does not attain its intended uses in the future as expected.

Comment:
On the current cover page for the draft public review “Now Available upon Request,” the short
summary needs to include a statement of how phosphorus is related to chlorophyll-a. For
instance, you could add to the last sentence of the summary so that it reads, “The study identifies
the sources of pollution, determines allowable loads to the surface waters, and suggest allocations
for total phosphorus which is limiting factor in the growth of algae as measured by chlorophyll-
a.” Otherwise, someone who is not as familiar with the background of the Robeson Creek TMDL
study might not make the connection between chlorophyll-a and phosphorus, since the
connection is not explained until page 7 of the report.

Response:
The referenced cover page is not included in the final TMDL. However, the document has been
revised to reflect this recommendation by adding language to the introduction chapter.

Comment:
We are concerned that extreme conditions for drought period (April – October) of 2002 were not
used in calculating the allowable Total Phosphorus load for the Robeson Creek cove. Streams are
most vulnerable to pollution problems during worst-case flows due to high or low water flows
during wet or dry weather conditions. Stream flow is an important part of this TMDL and to
protect Robeson Creek, it is critical that the worst-case flow is used.

Response:
Data was not available for September and October of 2002. Therefore while some of the data
from 2002 was used to test the model, the data were insufficient to calibrate the model and
accordingly derive the TMDL.

In addition, the allowable TP load to Roberson Creek Cove is based on critical conditions of a dry
summer. During 2001 (Apr – Oct), the average mean daily flow was 41% of the historical 43-
year average based on flow measured at the Tick Creek gage. During the same period of 2002,
Roberson (Robeson) Creek TMDL Final Report

flow was 44% of the historical average. However, based on the months April through September,
the percent of historic averages was 46% (2001) and 14% (2002). Clearly this period of 2002
was extremely dry. Most of the flow occurred during October of that year. In fact during the
period of June – July, flow during 2002 was 3% of the historical average. DWQ believes that the
Roberson Creek TMDL should not be based on such extreme hydrologic conditions.

Comment:
We believe it will be necessary to continue to monitor Turkey Creek and Camp Creek during
storm events due to run-off from Townsend Foods spray fields. Page 17 of the draft reports states
"Phosphorus from the irrigated wastewater transported via surface and subsurface runoff, appears
to have moved into Turkey Creek and Camp Creek. The results suggest that the pasturelands
owned by Townsend Food Inc. may have discharged considerable amount of P to Roberson
Creek during storm events in 2001." Although much of the runoff may occur normally in the
winter months, an unusually wet summer such as we are experiencing in 2003 could result in
more phosphorus loading from this source than anticipated.

Response:
The allowable TP load to Roberson Creek Cove is based on critical conditions of a dry summer
period. Dry hydrologic conditions in Roberson Creek Cove would tend to maximize residence
time and nutrient retention, thereby promoting algal growth. The average residence time during
2001 was 31 days. During wetter years, DWQ expects the residence time to decrease and
flushing to increase in the cove, lessening the potential for algal blooms. The TMDL established
during the critical condition will also protect water quality during other periods in terms of season
and hydrologic years.

Comment:
To insure timeliness in the implementation of this TMDL, a schedule of milestones for meeting
the TMDL needs to be included in the final draft. Even if the development of milestones for non-
point source pollution is part of the implementation plan that NCSU Water Quality Group is
working on, a schedule of milestones for the point source pollution should be included in the
TMDL report.

Response:
Roberson (Robeson) Creek TMDL Final Report

Comment refers to implementation. An implementation plan is not included in the TMDL
submittal for EPA approval. Monitoring will continue on a monthly interval at the ambient
monitoring site in the Roberson Creek Cove. The continued monitoring of nutrient and chl a
concentrations will allow for the evaluation of progress towards the goal of achieving water
quality standards and intended best uses.

3. Comments from David B. Hughes

Comment:
If the criteria for P is based on 10% exceedences for a typical year and the model is based on a
dry year (non-typical), it would seem that the criteria would be overly conservative. It would also
seem that an added margin of safety is even more conservative.

Response:
The TMDL target is based on the chlorophyll a criteria combined with current use assessment
methodology. Combining the two, no more than 10% of samples collected in a specified area and
time should be above 40 µg/L chl a. The TMDL is established for P because DWQ believes it is
the primary limiting nutrient in the cove. The allowable TP load to Roberson Creek Cove is based
on critical conditions of a dry summer period. Sufficient data for use as a basis for this TMDL
was only available for 2001. The chl a standard and intended uses in the cove should be met
during dry years and wet years. A margin of safety is a required component of TMDLs that
accounts for uncertainty.

Comment:
If flow data was underestimated, how would that affect the results?

Response:
The daily flows from the Tick Creek gage were adapted for use in the modeling of loads to the
Roberson Creek cove. Based on comparison with instantaneous flow data collected on Roberson
Creek, the adapted Tick Creek flow underestimated flow in Roberson Creek in part of late
summer and fall. However, most of these flows were below 5 cfs and the difference is not
expected to have a significant effect on loading estimates.

Roberson (Robeson) Creek TMDL Final Report

Comment:
The last paragraph on page 31 states that “since a term for light is not included in the candidate
models, predicted chl a may be overestimated.” What is the overestimation and how did the
calibration factor accurately account for this?

Response:
The chl a model is based on an empirical relationship between chl a and nutrients. An adjustment
is made to the model to account for site-specific conditions in Roberson Creek: the calibration
factor. The calibration factor (0.83) reduces the apparent chl a predicted by the model to more
closely match observed conditions: a typical calibration procedure in the modeling process. The
need for the calibration could have been due to the inhibitory influence of a diminished light field
within the water column.

Comment:
What does paragraph 3 and 4 of section 4.4, page 48, mean and what is the lack of agreement
between the models?

Response:
Models are merely tools used for system description and prediction. Uncertainty is always present
in model results. Decisions made based on model results should be made in light of model
limitations and uncertainty.

The SWAT model and the FLUX model produced different estimates of P load, however, the
estimates were within one standard error of each other. The SWAT model is a process model that
describes P transport in a mechanistic fashion. The model was calibrated to a P load derived from
regression using P load and flow. The FLUX model uses a statistical approach (modified ratio
estimator) to calculate load from daily flow values and biweekly P concentrations.

Comment:
The footnote below the chart on page 9 mentioned data is uncorrected for pheophytin, which may
overestimate the actual corrected value. What are the ramification for this?

Response:
Roberson (Robeson) Creek TMDL Final Report

Pheophytin is a component of algae representing dead cells. Due to problems with lab data, the
data from 1998-2000 are uncorrected for this component. There are no ramifications for the
TMDL because only data from 2001, which were corrected chl a concentrations, were used.

Comment:
Why was the BATHTUB model used in this study versus the WASP/EUTRO5 model used for
the Jordan Lake Nutrient Response study done by Tetra Tech, Inc.?

Response:
The Jordan Lake Nutrient Response model did contain sufficient spatial resolution to model the
Roberson Creek Cove. Further, the Jordan model development was not complete when
development of the Roberson Creek TMDL began.

Comment:
What other WWTP’s have had TMDL’s for either P or N applied to them? What limits were
applied to them? Were any of the plants comparable in size to Pittsboro’s plant? What were the
phase-in periods for compliance to the new limits?

Response:
Comments refer to implementation. An implementation plan is not included in the TMDL
submittal for EPA approval. DWQ’s NPDES permitting unit will provide the Town of Pittsboro
will information relating to these issues during the implementation phase.

Comment:
The implementation schedule must recognize the Town’s limited financial capabilities, and must
allow sufficient time for the Town to obtain funding necessary to upgrade the plant to achieve the
proposed P limitations. The town should be given an implementation time period that is at least
as long as the one provided to the dischargers in the Neuse Basin when the TN limit was imposed
there.

Response:
Comment refers to implementation. An implementation plan is not included in the TMDL
submittal for EPA approval.

Roberson (Robeson) Creek TMDL Final Report

Comment:
In the public meeting it was discussed that the Division is proposing the mass-based TP standards
from the TMDL model be implemented form April 1 – October 31, and that the existing 2.0 mg/L
quarterly average remain in place for the remaining months. The Town supports this proposal.

Response:
Comment refers to implementation. An implementation plan is not included in the TMDL
submittal for EPA approval.

4. Comments from Robert W. Slocum, Jr.

Comment:
We have reviewed the proposed TMDL for Roberson Creek in Chatham County and are pleased
that any contributions of phosphorus form forestry activities are considered as part of background
discharges. This is consistent with numerous scientific studies and recognizes that land disturbing
forestry activities in NC are regulated under the Sedimentation Pollution Control Act. As you
finalized this TMDL and develop others, we urge the agency to continue this approach to forestry
activities.

Response:

The TMDL identified forest lands as part of the background source of P in the watershed and did
not refer to any forestry activities specifically. The watershed model did not predict loading of P
to the cove from forest lands during the summer period of 2001.

Roberson (Robeson) Creek TMDL Final Report

Roberson (Robeson) Creek TMDL Final Report

11 References
Bachman, R.W. 1980. Prediction of total nitrogen in lakes and reservoirs. In Restoration of lakes
and inland waters; Proceedings of an international symposium on inland waters and lake
restoration. Portland, Maine. U.S. Environmental Protection Agency, Office of Water Regulations
and Standards, EPA-440-581-010, Washington, D.C.

Beale, E.M.L. 1962. Some uses of computers in operational research. Industrielle Organisation
31:51-52.

Butcher, J., T. Clements, A. Beach, K. Brewer, D. Korn, N. Archambault, and P. Kellar. 1995.
Falls Lake Watershed Study-Final Report. Prepared for the NC Department of Environment,
Health and Natural Resources. The Cadmus Group, Durham, NC.

Carlson, R.E. 1977. A trophic state index for lakes. Limnology and Oceanography 22:361-369.

Dodd, R.C., G. McMahon, and S. Stichter. 1992. Watershed planning in the Albemarle-Pamlico
Estaurine System. Report I – Annual Average Nutrient Budgets. Report No. 92-10. Albemarle-
Pamilco Estuarine Study. NC DEHNR. Raleigh, NC.

Ernst, M.R., W. Frossard, and J.L. Mancini. 1994. Two eutrophication models make the grade.
Water Environment and Technology. November, 15-16.

Giese, G.L. and R.R. Mason, Jr. 1993. Low-flow characteristics of streams in North Carolina.
U.S. Geological Survey water-supply paper 2403.

Hodgkins, Genn A. 2001. Total Phosphorus Loads for Selected Tributaries to Sebago Lake,
Maine. Water Resources Investigations Report 01-4003. U. S. Department of the Interior, USGS,
Augusta, Maine.

Illinois Environmental Protection Agency. 2002. Governor Bond Lake TMDL Report.

Kennedy, R.H. 1995. Application of the BATHTUB model to selected southeastern reservoirs.
Technical Report EL-94-14, U.S. Army Engineer Waterways Experiment Station, Vicksburg,
MS.

Luzio M. D., R Srinivasan, J. G. Arnold, and S. L. Neitsch. 2002. ArcView Interface For
SWAT2000, User’s Guide. Blackland Research and Extension Center. Texas Agricultural
Experimental Station. 720 East Blackland Road, Temple, Texas, 76502.

NCSU Water Quality Group. 2002. Roberson Creek Watershed Landuse Classification. Raleigh,
NC.

NC Department of Environment, Health and Natural Resources (DEHNR) and SC Department of
Health and Environmental Control. 1992. Water Quality Investigation of Lake Wylie. Report No.
92-04.

NC Division of Water Quality. 2002. Roberson Creek TMDL Study Final Report Memorandum.

Roberson (Robeson) Creek TMDL Final Report

Office of Water. 1997. Guidelines for preparation of the comprehensive state water quality
assessments. EPA-841-B-97-00. U.S. Environmental Protection Agency, Washington D.C.

Osborne, L. L. and D. A. Kovacic. 1993. Riparian Vegetated Buffer Strips in Water Quality
Restoration and Stream Management. Fresh Water Biology, 29:243-258.

Preston, S.D., V.J. Bierman, and S.E. Silliman. 1989. An evaluation of methods for the estimation
of tributary mass loads. Water Resources Research 25(6): 1379-1389.

Redfield, A. 1958. The biological control of chemical factors in the environment. Am. Sci.
45:205-221.

Research Triangle Institute. 1998. Eutrophication Modeling for the Randleman Lake Project.
Final Report submitted to the NC Department of Environment and Natural Resources, Division of
Water Quality. RTI, Research Triangle Park, NC. September 1998.

Reynolds, C.S. 1984. The Ecology of Freshwater Phytoplankton. Cambridge University Press,
Cambridge.

Tetra Tech. 2002. Jordan Lake Nutrient Response Model. Prepared for The Jordan Lake Project
Partners. Tetra Tech, Inc., Research Triangle Park, NC. November 2002.

Thomann, R.V. and Mueller, J.A. 1987. Principles of Surface Water Quality Modeling and
Control. Harper and Row, New York, NY.

U.S. Environmental Protection Agency (USEPA). 1991. Guidance for Water Quality-Based
Decisions: The TMDL Process. Assessment and Watershed Protection Division, Washington,
DC.

U.S. Environmental Protection Agency, Federal Advisory Committee (FACA). Draft final TMDL
Federal Advisory Committee Report. 4/28/98.

U. S. Environmental Protection Agency. 1999 Protocol for Developing Nutrient TMDLs.1st
Edition. Office of Water, Washington DC. EPA-841-B-88-007.

U.S. Environmental Protection Agency (USEPA) 2000a. Revisions to the Water Quality
Planning and Management Regulation and Revisions to the National Pollutant Discharge
Elimination System Program in Support of Revisions to the Water Quality Planning and
management Regulation; Final Rule. Fed. Reg. 65:43586-43670 (July 13, 2000).

U. S. Environmental Protection Agency. 2000b. Nutrient Criteria Technical Guidance Manual:
Lakes and Reservoirs. 1st Edition. Office of Water, Washington DC. EPA-822-B00-001.

U.S. Environmental Protection Agency (USEPA). 2001. Clean Air Status and Trends Network
(CASTNet) Annual Report. Prepared by Harding ESE, Inc. November 2002.

Walker,W.W. 1983. Empirical methods for predicting eutrophication in impoundments. Report 2,
Phase II: Model Testing. Technical Report E-81-9. U. S. Army Engineer Waterways Experiment
Station, Vicksburg, MS.

Roberson (Robeson) Creek TMDL Final Report

Walker, W.W. 1996. Simplified procedures for eutrophication assessment and prediction: User
manual. Instruction Report W-96-2, U. S. Army Engineer Waterways Experiment Station,
Vicksburg, MS.

Waschbusch, R. J., W. R. Selbig, and R. T. Bannerman. 1994-95. Sources of Phosphorus in
Storm water and Street Dirt from Two Urban Residential Basins in Madison, Wisconsin. USGS.
Water-Resources Investigation Report. 99-4021.

Wetzel, R.G. 2001. Limnology: Lake and River Ecosystems, 3rd Edition. Academic Press, San
Diego.

Yonts, W.L., Giese, G.L., and Hubbard, E.F. 1973. Evaporation from Lake Michie, North
Carolina, 1961-1971. U.S. Geological Survey Water Resources Investigations Report 38-73. 27 p.

Zar, J.H. 1999. Biostatistical Analysis. Fourth Edition. Prentice Hall, New Jersey.
Roberson (Robeson) Creek TMDL

Appendix I. Water quality data collected during the Roberson Creek TMDL Study (2000-2002).

Roberson Creek Physical/Chemical and Flow
See accompanying Qualifier Codes list

Station # &
Location
Sample
Date Time TKN TP TN BOD5 DO pH Temp Cond
Stage
feet Flow
fecal
MF Chl a
mg/L mg/L mg/L mg/L mg/l mg/L mg/L mg/L units C umhos
(RC8
only) cfs /100 ml ug/L

RC4 Hwy 15/501 00/12/14 1040 ns ns ns ns ns ns 10.3 7.2 5.6 127 ns ns
Roberson Cr 00/12/21 0915 0.12 0.4 0.24 0.04 0.64 2.2 6.4 11.8 6.9 3.3 109 ns 160
Lat 35o 42’ 57"
Long 79o 10’ 44"

RC5 ups 00/12/14 1050 0.02 0.4 0.13 0.04 0.53 ns ns 9.3 7.4 5.8 131 ns ns
Roberson Cr 00/12/21 1120 ns ns ns ns ns 6.4 10.8 7.2 3.2 129 ns 160
upstream WWTP 01/01/08 1045 0.02 0.4 0.37 0.04 0.77 1.1 7 11.5 6.8 2.4 141 0.71 27
Lat 35o 42’ 52" 01/01/18 1030 0.06 0.6 0.34 0.03 0.94 1.7 7.5 10.0 7.9 6.4 146 0.42 45
Long 79o 10’ 18" 01/01/25 1200 0.05 0.5 0.14 0.01 0.64 0.9 5.8 12.0 7.3 5.9 117 1.66 260
01/02/08 1115 Lab Lab <1.0 Lab 7.1 7.2 10.3 7.3 7.5 137 1.49 <10
01/02/13 1100 Lab Lab Lab <0.5 2.3 5.8 10.9 7.0 5.1 80 3.85 380
01/02/20 1150 Lab Lab Lab <0.5 3.5 6.6 10.7 7.2 8.6 110 3.68 2500
01/03/01 1100 <0.5 <1.0 <0.5 <0.5 <2 7.1 7.7 7.4 10.3 121 1.21 73
01/03/07 1045 0.55 <1.0 <0.5 <0.5 2.6 5.5 10.9 7.1 7.5 91 6.03 310
01/03/28 1240 <0.20 <0.6 0.3 <0.10 <2 5.5 10.7 7.9 10.8 94 2.78 22
01/04/18 1120 <0.20 0.8 0.29 <0.10 1.09 <2 6.2 9.3 8.1 11.9 109 1.69 220
01/05/02 1115 <0.20 <0.6 0.28 <0.10 1.2 7.1 6.3 7.4 19.9 122 0.89 110
01/05/09 1110 <0.20 <0.6 0.36 <0.10 1.3 8.6 11.5 8.1 19.1 270 0.62 57Q
01/05/30 1030 <0.20 <0.6 0.15 <0.10 3.0 6.9 4.2 7.1 19.4 106 0.91 520
01/06/21 1050 0.11 0.5 0.29 0.03 0.76 1.6 6 5.6 7.1 24.3 100 0.16 470
01/08/07 1115 0.09 0.5 0.38 0.04 0.85 7.2 6.5 3.8 7.0 23.8 115 0.45 520
01/08/30 1040 0.04 0.7 0.16 0.06 0.86 2.1 5.2 5.0 7.2 25.3 104 1.98 430
01/10/04 1050 0.04 0.4 0.33 0.04 0.72 ns 6.1 9.0 6.8 16.6 125 0.49 250
01/11/07 1130 0.02 0.2 0.21 0.02 0.45 1.0 6.7 7.8 7.3 10.3 138 0.35 54 B1
Roberson (Robeson) Creek TMDL

01/11/14 1120 0.05 0.3 0.26 0.02 0.57 1.3 6.5 8.9 6.8 4.4 137 0.90 73 Q
01/12/11 1100 0.18 0.4 0.1 0.05 0.51 2.6 ns 12.3 7.2 6.3 103 1.10 2200
02/01/10 1125 0.06 0.4 0.37 0.05 0.76 1.3 G5 ns 14.7 6.9 1.9 177 2.78 1800 B1
02/02/05 1135 0.05 0.3 0.38 0.04 0.72 1.9 G5G1 ns 9.6 7.2 6.1 108 2.75 46 Q1
02/03/08 1215 0.14 0.4 0.25 0.04 0.63 1.6 ns 11.2 7.0 6.7 114 0.62 49
02/04/15 1110 0.08 0.4 0.28 0.05 0.67 1.5 ns 8.4 7.0 20.3 61 0.52 190
02/05/01 1040 0.08 0.5 0.35 0.04 0.80 1.6 ns 5.3 7.1 17.4 164 no flow120
02/06/26 1010 0.09 0.5 0.38 0.04 0.86 1.6 ns 3.4 7.1 23.8 355 no flow340 B4

RC5 eff 00/12/21 1110 0.22 1.1 16 0.67 17.10 ns 55 10.0 6.8 11.0 487 <10
WWTP effluent 01/01/08 1000 0.48 5.5 16 1.80 21.50 1.2 58 9.4 7.2 11.1 480 <10
Lat 35o 42’ 49" 01/01/18 1020 0.04 1.6 31 3.20 32.60 1.8 64 9.9 7.8 12.4 543 <10
Long 79o 10’ 14" 01/01/25 1145 ns ns ns ns ns ns 8.5 7.2 11.4 460
01/02/08 1145 Lab 1.1 Lab 3.20 6.3 50 7.2 6.4 13.0 491 10k
01/02/13 1130 Lab Lab Lab Lab 3.8 48 10.2 7.1 12.0 306 10k
01/02/20 1130 Lab Lab Lab Lab 4.2 56 9.7 7.0 12.5 389 160
01/03/01 1040 ns ns ns ns ns ns 9.2 ns 13.6 694
01/03/07 1100 0.80 3.0 26 1.00 29.00 6.6 55 9.8 7.1 11.8 507 100
01/03/28 1250 0.28 3.2 42 3.60 45.20 6.6 110 9.9 7.3 14.0 643 250
01/04/18 1100 0.79 8.9 53 9.00 61.90 2.1 190 8.8 6.4 16.3 995 2700
01/05/02 1100 0.37 4.5 48 2.80 52.50 10.4 180 9.2 7.0 17.8 990 430
01/05/09 1100 <0.20 3.3 43 3.10 46.30 3.6 210 8.3 7.1 19.9 1122 Lab
01/05/30 1000 <0.20 1.7 41 3.00 42.70 ns 160 5.8 7.0 21.5 927 4
01/06/21 1025 0.12 1.2 23 1.90 24.20 1.0 120 7.2 7.6 23.6 676 12
01/08/07 1045 0.05 2.0 19 2.60 21.00 2 U 81 7.3 7.6 25.6 440 17
01/08/30 1015 0.02 0.2 15 0.80 15.20 1.0 52 7.5 7.0 24.0 442 4
01/10/04 1025 0.01 U
0.20
U 22 1.80 ns 77 8.0 7.2 21.2 599 22
01/11/07 1045 0.03
0.20
U 24 1.60 0 J2 10.3 6.8 17.7 661 1
01/11/14 1055 0.01
0.20
U 18 1.40 1 170 12.2 6.6 16.2 728
02/02/05 1115 0.06 0.3 32 3.20 32.28
3.7J2G1G
5 ns 7.9 ns 12.9 886 5Q1
02/01/10 1100 0.04 6.6 25 1.60 31.60 0.4 G5 ns 11.0 7.1 7.6 737 2
02/03/08 1100 0.12 0.4 2.4 0.20 2.79 1.6 ns 8.7 7.2 13.6 718 44
02/04/15 1050 0.07 0.4 2.3 0.30 2.73 1.2 ns 10.1 7.1 17.9 666 3
Roberson (Robeson) Creek TMDL

02/05/01 1010 0.42 .20 U 20 1.90 1,7 ns 8.3 7.1 19.4 784 1 B2
02/06/26 1000 0.03 0.4 26 3.90 26.41 1.3 ns 4.3 6.6 25.2 838 9
02/08/15 1000 0.02 0.8 30 4.20 30.84 ns ns

RC5 dns 00/12/14 1100 0.02 0.9 8.8 0.66 9.70 1.5 ns 8.0 7.1 5.6 256 ns
Roberson Cr 00/12/21 1055 0.05 0.6 4 0.18 4.60 ns 15 10.7 7.1 4.6 210 1.69 200
downstream
WWTP 01/01/08 1015 0.80 1.1 7 0.67 8.10 1.3 30 10.1 7.0 5.6 280 1.00 82
Lat 35o 42’ 50" 01/01/18 1015 0.31 1.0 9 1.00 10.00 1.7 31 9.5 7.6 8.7 318 1.07 64
Long 79o 10’ 08" 01/01/25 1125 0.05 0.6 3.6 0.31 4.20 0.8 12 12.0 7.0 6.1 178 2.66 140
01/01/30 1300 <0.01 0.8 7.1 0.76 7.90 0.7 19 10.6 7.1 9.9 252 2.27 27
01/02/08 1135 Lab <1.0 Lab Lab 6.9 21 10.1 7.0 9.0 277 1.37 27
01/02/13 1115 Lab Lab Lab <0.5 2.5 13 12.3 7.4 6.5 115 4.89 340
01/02/20 1115 ns ns ns ns ns ns 10.4 7.6 8.9 177 4.63 ns
01/03/01 1030 0.95 2.3 8.8 0.90 11.10 2.3 25 10.2 7.5 9.0 237 2.22 73
01/03/07 1100 <0.5 <1.0 3.2 <0.5 3.0 14 10.3 7.4 8.8 132 7.55 480
01/03/28 1350 <0.20 1.0 9.1 0.69 10.10 2.1 25 10.3 7.8 11.5 232 3.92 40
01/04/18 1110 0.36 3.4 11 2.20 14.40 6.7 44 8.4 7.0 12.4 321 2.23 3000
01/05/02 1040 0.20 2.0 20 1.10 22.00 5.2 83 7.4 7.8 18.0 604 1.56 250
01/05/09 1045 <0.20 2.3 24 1.60 26.30 2.2 120 6.9 7.3 18.1 448 0.90 48Q
01/05/30 1020 <0.20 1.3 17 1.10 18.30 2.3 56 4.4 7.0 19.6 376 1.46 360
01/06/21 1015 0.08 0.7 9.6Q 0.78 1.2 52 5.3 7.3 21.0 343 0.33 420
01/08/07 1035 0.15 0.6 8.9 1.10 9.52 2 U 28 3.3 7.2 23.8 272 0.74 320
01/08/30 1020 0.03 0.6 3.2 0.19 3.82 1.0 15 5.3 7.0 25.0 171 2.49 460
01/10/04 1030 0.03
0.22
U 9 0.66 ns 34 7.7 6.7 18.1 320 0.77 250
01/11/07 1100 0.04
0.20
U 13 0.83 0.7 63 8.2 7.1 13.5 409 0.63 28
01/11/14 1105 ns ns ns ns ns ns 9.3 6.5 7.6 417 2.21 ns
01/12/11 1045 0.08 0.5 1.8 0.16 2.25 2.2 ns 10.3 7.0 6.5 165 2.40 3100
02/01/10 1105 0.34 1.5 4.1 0.29 5.60 1.9 G5 ns 14.8 7.0 2.1 272 3.92 730
02/02/05 1120 0.05 0.4 6.7 0.63 7.11 2.1 ns 6.4 7.2 7.1 262 3.78
68
B4Q1
02/03/08 1120 0.08 .20 U 18 1.50 1.2 ns 11.4 7.1 9.2 198 2.20 16
02/04/15 1030 0.05 .20 U 14 1.70 1.4 ns 7.3 7.0 20.0 214 1.92
65 B4
Q1
02/05/01 1000 0.06 0.4 7.3 0.59 7.70 ns ns 6.1 7.0 18.2 306 0.98 97
Roberson (Robeson) Creek TMDL

02/06/26 0950 0.06 .20 U 14 2.00 1.6 ns 5.2 7.0 23.0 586 0.42 310 B4
02/08/15 1015 0.03 0.8 20 2.70 20.75 ns ns

TC1 00/12/14 1010 0.04 0.3 0.05 0.04 0.35 1.2 ns 10.0 7.3 5.0 118 ns ns
Turkey Cr at 00/12/21 0930 0.04 0.6 0.01 0.03 0.61 ns 5.4 12.9 7.0 0.9 ns 0.56 210
Hwy 15/501 00/12/28 1040 0.10 0.5 0.21 0.04 0.71 1.2 ns 12.0 7.2 2.2 102 ns 38
Lat 35o 42’ 06" 01/01/08 0900 0.02 0.3 0.2 0.03 0.50 1.0 6.8 11.9 7.3 1.7 111 0.06 130
Long 79o 10’ 48" 01/01/18 0910 0.05 0.4 0.11 0.02 0.51 1.1 6.2 11.1 7.6 5.7 96 0.05 27
01/01/25 1015 0.05 0.4 0.15 0.01 0.55 0.5 6.9 13.2 7.1 2.2 97 0.20 71
01/01/30 1015 0.01 0.5 0.17 0.04 0.67 0.7 6.7 10.6 7.2 8.0 103 0.18 64

01/02/08 1000 0.00 <1.0 <0.5 <0.5 6.9 7.7 11.5 6.8 5.2 107 0.15 14
01/02/13 1030 Lab Lab Lab <0.5 2.8 7.8 11.8 7.0 5.2 61 4.15 380
01/02/20 0830 Lab Lab Lab <0.5 1.2 6.5 11.9 7.0 5.2 83 0.52 160
01/03/01 0830 <0.5 <1.0 <0.5 <0.5 <2 8.2 10.2 7.1 8.0 97 0.42 260
01/03/07 0930 0.80 1.3 <0.5 <0.5 <2.0 6 12.3 7.9 4.4 77 1.56 220
01/03/28 0830 <0.20 <0.6 0.15 <0.10 <2.0 6.5 12.4 7.2 6.0 89 0.55 74
01/04/18 0845 0.20 U
0.60
U 0.15 0.10 U 2.1 7.4 10.2 7.5 9.0 100 0.19 150
01/05/02 0830 <0.20 <0.6 <0.15 <0.10 1.0 8.2 6.8 7.1 15.7 110 0.16 150
01/05/09 0845 <0.20 <0.6 <0.15 <0.10 1.1 8.5 6.7 7.5 15.3 114 0.04 200Q
01/05/30 0840 <0.20 <0.6 0.17 <0.10 ns 7.7 5.4 7.5 17.6 106 0.09 1900 B1
01/06/21 0830 0.06 0.4 0.19 0.03 0.59 1.0 6.5 5.0 7.0 21.7 105 0.09 240
01/08/07 0857 0.32 0.6 0.11 0.06 0.69 0.7 6.5 4.2 6.9 23.0 45 0.05 57 J2
01/08/30 0900 0.03 0.3 0.19 0.05 0.51 0.4 5.6 5.3 7.1 22.8 87 0.31 240
01/10/04 0900 0.01 U 0.3 0.14 0.03 0.42 ns 5.9 6.9 7.3 14.7 180 0.11 240 Q
01/11/07 0915 0.14 J3 0.3 0.02 0.02 0.32 0.9 J2 7.2 8.5 7.1 7.2 123 0.05 9 Q
01/12/11 0900 ns ns ns ns ns ns 10.9 7.2 4.3 115 no flow
02/01/10 0910 0.07 0.8 0.24 0.05 1.05 1.1 G5 ns 16.6 7.1 2.3 98 0.45 770 B4
02/02/05 0940 0.03 0.2 0.29 0.03 0.49 1.1J2G1 ns 12.6 7.1 3.0 93 0.51 33Q1
02/03/08 0910 0.20 0.4 0.12 0.03 0.47 1.1 ns 13.2 7.1 6.0 102 no flow
110 Q2
B4
02/04/15 0840 0.26 0.3 0.12 0.04 0.41 1.4 ns 8.5 7.4 17.0 106 no flow67 Q2
02/05/01 0830 0.06 0.3 0.22 0.03 0.54 ns ns 7.2 7.2 16.4 120 0.06 120

TC2 00/12/14 0945 6.90 7.9 1.9 1.40 9.80 34.4 ns 6.8 7.1 5.2 1425 ns ns
Roberson (Robeson) Creek TMDL

Turkey Cr at 00/12/21 1015 1.20 3.2 1.1 0.47 4.30 ns 22 12.9 7.2 1.2 ns 0.62 620
SR 1012 00/12/28 1010 10.00 14.0 2.3 4.20 16.30 59.0 87 11.2 7.2 2.0 761 ns 5300
Lat 35o 42’ 15" 01/01/08 0945 0.97 1.2 1.3 0.42 2.50 6.6 38 10.8 7.2 2.8 370 0.16 410
Long 79o 10’ 30" 01/01/18 0920 0.80 1.3 1.2 0.33 2.50 4.2 49 9.4 7.9 6.1 397 0.14 82
01/01/25 1030 1.00 2.0 1.6 0.47 3.60 6.6 38 13.2 7.2 3.2 348 0.31 140
01/01/30 1030 11.00 13.0 2.9 3.90 15.90 25.0 85 8.3 7.6 8.5 860 1.44 140
01/01/30 1250 8.50 11.0 3 2.80 14.00 24.0 81 10.4 7.3 10.1 760 ns 2400
01/02/08 1020 <0.5 Lab <0.5 <0.5 7.3 30 11.9 7.2 6.1 317 0.22 64
01/02/13 0930 Lab Lab Lab <0.5 3.7 14 12.7 7.6 5.7 164 3.67 740
01/02/20 0900 Lab Lab Lab <0.5 0.9 12 12.3 7.3 5.2 142 0.87 320
01/03/01 1000 1.50 2.0 0.95 <0.5 2.95 4.6 15 9.6 7.8 9.2 187 0.50 590
01/03/07 1215 Lab 1.8 0.66 <0.5 2.46 2.6 9.9 11.6 8.1 7.1 126 1.58 270
01/03/28 1100 0.29 <0.6 0.76 <0.1 2.4 9.6 10.8 7.6 9.4 129 0.56 360
01/04/18 1030 3.50 3.9 1.8 <0.10 5.70 5.8 14 9.8 7.9 10.5 197 0.54 230
01/05/02 1010 3.50 3.9 3.6 <0.10 7.50 4.3 14 5.4 7.9 16.3 209 0.09 210
01/05/09 1030 4.70 5.7 2.4 0.23 8.10 9.6 22 4.0 7.0 15.6 271 0.10 Lab
01/05/30 0945 6.00 6.5 1.6 0.29 8.10 22.0 17 3.7 7.0 17.0 242 0.14 360
01/06/21 0950 12.00 Lab 3.2 0.26 12.0 17 3.3 7.1 22.2 267 0.14 3000
01/08/07 1020 0.09 0.5 1.1 0.12 1.55 2.4 18 5.4 7.3 23.4 209 0.14 120 B1
01/08/30 1000 0.14 1.3 1 0.30 2.30 1.1 17 5.7 7.1 23.3 175 0.28 190 B1
01/10/04 1000 0.21 1.0 0.77 0.16 1.77 ns 13 6.8 6.8 15.2 193 0.14
190
QB4
01/11/07 1040 0.11 0.3 0.43 0.08 0.76 0.8 36 7.1 7.1 8.6 315 0.08 34
01/11/14 1040 2.80 6.1 0.95 0.49 7.05 3.1 79 8.0 6.9 4.2 485 0.09 460 Q
01/12/11 1020 0.42 2.1 1.8 1.00 3.90 8.4 ns 11.2 6.9 4.8 440 0.54
10000
B3
02/01/10 1040 1.40 1.8 0.42 0.08 2.22 1.2 G5 ns 15.8 7.2 1.5 154 0.56 420
02/02/05 1055 0.66J3 0.8 0.52 0.05 1.36 1.2 ns 12.7 7.2 3.7 136 0.54
130
B4G1
02/03/08 1045 0.62 1.0 0.34 0.06 1.34 1.6 ns 11.6 7.0 8.9 167 no flow80 B4
02/04/15 1015 0.17 0.7 0.67 0.08 1.32 2.2 ns 10.1 7.0 19.1 165 no flow630 B4
02/05/01 0935 ns 5.2 7.2 16.6 315 no flow170
02/06/26 0930 0.02 0.4 0.85 0.09 1.23 0.8 no flow13

TC3 01/02/20 1000 Lab Lab 0.56 <0.5 2.0 11 12.3 7.0 6.6 127 1.10 1200
Turkey Cr at mouth 01/03/01 0945 Lab Lab Lab Lab 2.7 13 9.8 8.0 8.4 188 0.58 6300
Lat 35o 42’ 25" 01/03/07 1015 0.64 1.1 0.83 <0.5 1.93 2.5 9.2 12.4 7.3 5.8 116 2.22 180
Roberson (Robeson) Creek TMDL

Long 79o 09’ 49" 01/03/28 1010 4.30 4.5 2.7 <0.10 7.20 <2 9.8 11.2 7.4 8.3 160 0.72 58
01/04/18 1000 0.55 1.3 2.2 0.10 U 3.50 <2 9.9 11.5 7.3 10.6 139 0.58 52
01/05/02 0945 <0.2 <0.6 1.6 <0.10 1.1 11 9.6 7.2 15.3 140 0.25 43
01/05/09 1000 <0.2 <0.6 0.67 <0.10 0.8 13 8.2 7.2 15.4 162 0.15 240 Q
01/05/30 0930 0.43 1.1 2.9 <0.10 4.00 2.2 17 6.6 7.5 16.8 212 0.26 140B1
01/06/21 0930 0.14 0.6 0.59 0.12 1.16 0.7 10 7.9 7.2 21.2 139 0.25 2600
01/08/07 0847 0.04 0.3 0.39 0.09 0.70 2 U 11 5.2 7.2 22.1 109 0.13 310
01/08/30 0940 0.03 0.4 0.5 0.08 0.87 1.0 8.4 6.8 6.9 22.5 117 0.45 360
01/10/04 0945 0.01 U 0.6 1 0.21 1.59 2.3 24 7.3 7.2 14.2 260 0.17 980 B4
01/11/07 1010 0.02 0.4 0.15 0.08 0.51 1.0 16 12.5 7.1 7.0 203 0.13 ns
01/11/14 1020
0.01
UJ3
0.20
U 0.16 0.04 0.7 17 11.9 7.1 7.2 211 0.59 34 Q
01/12/11 1000 0.25 J3 0.9 0.76 J3 0.20 3.3 ns 10.9 7.2 4.7 200 0.60 4100
02/01/10 1015 11.00 12.0 0.48 0.17 12.48 0.2 G5 ns 15.3 7.2 1.2 475 0.72 5
02/02/05 1035 18.00 56.0 0.6 0.14 56.60 2.2 G5G1 ns 11.6 7.2 4.3 637 0.59
660 B4
Q1
02/03/08 1045 0.20 0.6 0.63 0.05 1.23 1.5 ns 11.6 7.0 8.9 157 0.12 230
02/04/15 1000 1.2 ns 11.6 7.0 18.9 130 no flow56
02/05/01 0920 ns ns 8.3 7.5 16.9 160 0.17 60
02/06/26 0910 2.10 2.7 1.2 0.12 3.90 6.6 ns no flow51

CC2 left 00/12/28 1035 0.18 0.4 0.56 0.07 0.96 ns ns 14.0 7.6 1.5 230 ns ns
Camp Cr. upstream 01/01/08 0915 0.02 0.3 0.06 0.04 0.36 0.6 20 12.9 7.3 1.4 187 0.07 36
from UT that drains01/01/18 0940 0.13 0.4 0.05 0.02 0.45 0.5 15 9.4 7.9 5.6 152 0.10 27
Townsend property 01/01/25 1100 <0.01 0.5 0.19 0.02 0.69 0.2 19 14.4 7.1 3.0 197 0.11 100
Lat 35o 41’ 42" 01/01/30 1115 0.06 0.6 1.1 0.06 1.70 0.1 22 11.8 7.1 8.8 200 0.17 73
Long 79o 09’ 32" 01/01/30 1230 0.01 0.9 1 0.04 1.90 0.3 22 13.0 7.2 10.0 213 ns 500
01/02/08 1040 <0.5 <1.0 0.74 <0.5 7.4 18 13.4 7.4 5.5 195 0.13 10k
01/02/13 1000 Lab Lab Lab <0.5 2.2 14 13.0 7.1 5.1 140 3.89 850
01/02/20 0915 Lab Lab <0.5 <0.5 0.5 10 12.4 7.5 5.3 114 0.63 180
01/03/01 0900 <0.5 <1.0 <0.5 <0.5 <2 13 11.5 8.0 7.4 136 0.32 45
01/03/07 0900 <0.5 <1.0 <0.5 <0.5 <2.0 8.6 12.8 7.2 4.5 97 1.32 120
01/03/28 0900 <0.20 <0.6 <0.15 <0.10 <2.0 7.3 12.8 7.3 5.0 91 0.43 10
01/04/18 0900 <0.20 <0.6 <0.15 <0.10 <2 7.2 11.0 6.6 8.0 92 0.14 86
01/05/02 0900 <0.20 <0.6 <0.15 <0.10 0.7 8.2 8.8 7.3 14.2 99 0.07 95
01/05/09 0910 <0.20 <0.6 <0.15 <0.10 0.4 8.7 7.6 6.9 14.0 101 0.04 260Q
01/05/30 0840 <0.20 <0.6 0.27 <0.10 ns 8.7 8.4 7.5 15.9 101 0.20 91 B4
Roberson (Robeson) Creek TMDL

01/06/21 0900 0.04 0.4 0.22 0.04 0.58 0.5 7.7 7.9 7.3 20.5 95 0.13 39
01/11/07 0940 0.04 0.6 0.09 0.66 0.68 0.8 70 12.2 7.0 7.0 170 0.06 370
01/11/14 0930 0.04 0.6 0.15 0.09 0.78 3.8 ns 14.0 7.2 2.4 145 0.08
10000
B3
01/12/11 0915 ns 13.4 7.2 4.3 115 0.11 ns
02/01/10 0940 0.02 0.3 0.7 0.04 1.03 0.8 G5 ns 16.5 7.0 1.4 129 0.43 560
02/02/05 1000 ns 12.6 7.2 12.6 95 0.43 ns
02/03/08 0955 0.01 .20 U .01 U 0.02 1.1 ns 11.8 7.0 15.3 100 0.10 49 Q2
02/04/15 0855 0.08 0.5 0.06 0.03 0.52 0.7 ns 9.8 7.1 17.4 106 no flow15 Q2
02/05/01 0900 0.03 0.3 0.28 0.03 0.56 ns ns 8.1 7.0 15.6 107 0.08 8

CC2right 00/12/28 1030 15.00 31.0 4.1 5.40 35.10 ns ns 11.8 7.3 1.7 956 ns ns
Ut that drains 01/01/08 0915 2.70 4.5 4.2 1.30 8.70 1.6 65 9.7 7.4 1.6 763 0.06 130
Townsend property 01/01/30 1100 11.00 13.0 4.7 3.50 17.70 23.0 90 10.2 7.4 9.2 880 1.19 1000
Lat 35o 41’ 47" 01/01/30 1215 9.70 12.0 5.2 3.50 17.20 16.0 93 9.3 7.3 10.4 860 ns 730
Long 79o 09’ 39" 01/02/08 1045 <0.5 1.0 1.2 1.30 2.20 7.5 69 10.9 7.5 5.4 771 ns 18
01/02/13 1000 Lab Lab Lab 0.90 4.3 56 13.1 7.4 5.1 550 0.50 260
01/02/20 0915 Lab Lab 1.6 0.65 0.5 49 11.9 7.2 4.5 548 0.11 290
01/03/01 0915 <0.5 Lab 0.63 0.87 <2 57 11.1 8.2 6.6 607 0.07 590
01/03/07 0905 <0.5 <1.0 <0.5 <0.5 <2.0 9.1 12.4 7.7 3.8 442 0.10 10K
01/03/28 0915 ns ns ns ns ns ns 12.6 7.4 3.6 432 0.02 ns
01/04/18 0910 <0.20 0.8 <0.15 0.81 <2 32 10.3 7.4 8.0 357 ns 51
01/11/07 0925 0.04 0.3 0.01 U 0.02 0.4 12 9.0 7.3 7.4 600 ns 150
01/11/14 0945 0.05 2.3 2.3 1.4 J3 4.60 6.3 ns 8.2 6.8 2.9 621 ns 6800 3
01/12/11 0920 0.05 2.3 2.3 1.4 J3 4.60 6.3 ns 12.1 6.8 4.6 665 ns 6800 B3
02/01/10 0930 0.02 1.1 1 0.44 2.10 0.9G5 ns 15.5 6.9 1.2 480 0.37 350
02/02/05 1010 0.02
0.20
U 0.02 0.22 0.7 G5G1 ns 12.8 7.2 2.1 403 0.30
140 B4
Q1
02/03/08 0930 .01 U 0.2 .01 U 0.15 0.7 ns 12.6 7.0 5.3 560 ns
920 B4
Q2
02/04/15 0905 0.04 0.4 0.18 0.31 0.58 0.1 ns 8.5 7.3 17.0 419 ns 250 B4

CC2 bridge 00/12/14 1000 0.83 1.9 3.5 1.00 5.40 6.50 ns 10.1 7.4 4.8 559 ns ns
Camp Cr at SR
1012 00/12/21 1000 1.60 3.6 1.9 0.80 5.50 ns 40 13.2 7.0 0.6 ns 0.43 590
00/12/28 0950 ns ns ns ns ns ns 11.8 7.3 1.7 956 ns ns
Roberson (Robeson) Creek TMDL

that
drains Townsend 01/01/18 0950 1.40 4.3 6 1.60 10.30 10.0 68 10.7 8.1 5.8 584 0.23 780
property 01/01/25 1115 0.87 1.5 2 0.47 3.50 0.1 40 13.1 7.2 2.7 440 ns 130
Lat 35o 41’ 49" 01/01/30 1130 8.70 11.0 4.3 2.90 15.30 15.0 80 10.4 7.2 9.6 740 1.36 780
Long 79o 09’ 33" 01/02/08 1100 Lab <1.0 Lab <0.5 7.5 34 12.5 7.5 5.8 346 0.14 10k
01/02/13 1015 Lab Lab Lab <0.5 1.9 19 12.0 7.3 5.9 340 ns 790
01/02/20 0930 Lab Lab <0.5 <0.5 0.6 14 12.9 7.2 5.4 178 ns 250
01/03/01 0920 <0.5 Lab <0.5 <0.5 <2 18 11.4 8.1 7.3 209 ns 350
01/03/07 0925 <0.5 <1.0 <0.5 <0.5 <2.0 11 11.2 7.7 7.5 240 ns 170
01/03/28 0925 0.20 1.4 <0.15 <0.10 <2 8.9 12.5 7.4 5.0 119 ns 80
01/04/18 0920 <0.20 <0.6 <0.15 0.10 <2 9 ns ns ns ns ns ns

CC3 01/02/20 1010 Lab Lab 0.25 <0.5 0.7 14 12.9 7.6 6.4 166 0.92 280
Camp Cr at mouth 01/03/01 1000 <0.20 <0.6 <0.15 0.14 <2 9.4 12.2 7.4 7.7 198 0.46 500
Lat 35o 42’ 16" 01/03/07 1000 <0.5 <1.0 <0.5 <0.5 <2.0 11 12.3 7.1 4.9 140 1.81 220
Long 79o 09’ 32" 01/03/28 1000 ns ns ns ns ns ns 13.1 7.7 6.1 121 0.59 ns
01/04/18 0930 <0.20 <0.6 <0.15 0.21 <2 9.4 12.0 7.5 8.2 109 0.30 50
01/05/02 0930 <0.20 0.6 <0.15 0.30 1.1 9 8.6 7.5 15.0 122 0.15 200
01/05/09 0940 <0.20 <0.6 0.24 0.42 0.9 8.6 7.2 6.9 15.0 126 0.08 99 B4,Q

01/05/30 0915 <0.20 <0.6 0.29 0.38 ns 12 8.2 7.3 16.5 143 0.22 680 B4
01/06/21 0910 0.03 0.4 0.23 0.35 0.60 0.5 9.6 7.3 7.3 20.8 96 0.20 320
01/08/07 0920 0.08 0.4 0.23 0.35 0.65 2 U 9 6.0 7.1 21.8 121 0.03 91 B4
01/08/30 0925 0.02 0.4 0.18 0.20 0.55 0.2 9.3 7.3 7.0 22.0 119 0.30 580
01/10/04 0930 0.03 0.3 0.31 0.29 0.61 2.8 12 6.7 7.1 14.0 156 0.06 5700
01/11/07 1005 0.30 0.8 0.04 0.18 0.82 0.6 18 10.4 7.2 8.0 200 0.11 1400 B1
01/11/14 1000 0.01 1.0 0.05 0.16 1.05 2.0 24 13.1 6.9 2.7 253 0.15 4900 Q
01/12/11 0940 0.03 0.8 0.47 J3 0.37 2.9 ns 12.4 7.2 4.6 212 0.51 7600 B3
02/01/10 1000 0.04 1.0 0.75 0.10 1.75 1.1 G5 ns 16.4 7.1 1.4 189 0.53 450
02/02/05 1020 0.12 0.3 0.09 0.04 0.34 0.8 G5G1 ns 12.8 7.2 2.8 120 0.55 440 Q1
02/03/08 1000 0.02 .20 U 0.01 0.03 0.9 ns 13.3 7.0 6.1 125 no flow
79 B4
Q2
02/04/15 0930 0.03 0.3 0.1 0.07 0.42 1.2 ns 17.5 10.8 7.1 121 no flow2600 B3
02/05/01 0910 0.04 0.3 0.28 0.14 0.55 ns ns 7.8 7.1 15.9 132 no flow870

RC8 staff 00/12/14 1130 0.39 1.0 5.1 0.33 6.10 ns ns 12.9 7.5 5.4 344 ns ns ns
Roberson (Robeson) Creek TMDL

Roberson Cr near 00/12/21 0850 0.72 1.4 1.6 0.29 3.00 ns 21 12.8 7.2 1.0 ns ns ns 530
Lucian Bland Rd 00/12/28 0915 ns ns ns ns ns ns 13.8 7.4 1.4 ns 1.58 3.41 ns
Lat 35o 42’ 05" 01/01/08 0830 0.52 1.0 4.3 0.42 5.30 1.2 24 11.1 7.1 2.0 302 1.46 1.62 45
Long 79o 07’ 49" 01/01/11 1030 ns ns ns ns ns ns 10.9 7.2 3.4 384 1.44 1.36 ns
01/01/18 0935 0.02 0.9 4.3 0.45 5.20 1.2 27 10.8 7.9 5.4 288 1.47 1.23 18
01/01/25 0940 0.16 0.8 2.2 0.26 3.00 0.5 16 13.5 6.8 3.1 170 1.71 5.65 100
01/01/26 1000 ns ns ns ns ns ns 14.3 7.2 1.7 264 1.51 2.43 ns
01/01/30 0930 1.40 5.3 3.6 0.66 8.90 4.0 27 12.0 7.1 6.9 318 1.58 3.42 82
01/02/08 0930 Lab <1.0 Lab <0.5 7.5 16 13.0 7.2 4.9 220 2.34 2.34 10k
01/02/13 0840 Lab Lab Lab <0.5 9.2 20 11.2 7.3 5.5 231 2.04 18.17 420
01/02/15 0930 ns ns ns ns ns ns ns ns ns ns 1.86 10.68 ns
01/02/20 1230 Lab Lab Lab <0.5 1.2 11 11.6 7.3 9.5 136 1.82 9.00 390
01/03/01 1300 <0.5 <1.0 2.5 <0.5 <2 15 10.8 7.7 11.5 195 1.64 3.83 100
01/03/05 1330 ns ns ns ns ns ns ns ns ns ns 2.64 49.75 ns
01/03/07 1315 <0.5 <1.0 1.3 <0.5 <2 9 11.8 7.0 9.2 128 1.98 13.75 360
01/03/21 0800 ns ns ns ns ns ns ns ns ns ns 5.2 448.17 ns
01/03/21 0940 ns ns ns ns ns ns ns ns ns ns 4.45 297.49 ns
01/03/21 1145 ns ns ns ns ns ns ns ns ns ns 3.75 203.46 ns
01/03/28 1330 <0.20 0.6 4 0.21 4.60 <2 14 12.1 7.2 11.9 136 1.75 6.58 28
01/03/30 0845 ns ns ns ns ns ns ns ns ns ns 5.95 547.31 ns
01/03/30 1005 ns ns ns ns ns ns ns ns ns ns 5.31 474.36 ns
01/04/18 1245 <0.20 <0.6 5.8 0.35 <2 16 12.6 8.1 12.9 185 1.62 3.65 ns
01/05/02 1300 <0.20 0.8 7.7 0.38 8.50 1.5 40 12.6 8.1 19.3 314 1.58 3.42 15
01/05/09 1300 <0.20 0.7 4.6 0.28 5.30 1.3 40 11.5 8.1 19.1 270 1.52 2.34 58
01/05/30 1130 <0.20 1.0 11 0.84 12.00 ns 44 7.1 7.1 20.2 305 1.54 2.88 ns
01/06/21 1230 0.33 0.9 1.7 0.20 2.59 <2.0 18 8.1 7.3 25.2 160 1.52 2.34 140B1
01/07/04 1530 0.03 0.7 0.4 0.09 1.06 ns ns 9.5 7.1 25.8 230 3.7 187.00 ns
01/07/23 1730 0.06 0.6 2.5 0.16 3.05 ns ns 8.9 7.0 26.2 281 1.56 3.00 ns
01/07/12 1830 0.29 0.5 1.3 0.11 1.78 ns ns 10.2 7.4 26.0 260 1.56 3.00 ns
01/07/31 1830 0.13 0.5 2.2 0.22 2.74 ns ns 9.1 7.2 26.2 234 1.60 3.56 ns
01/08/05 1415 0.04 0.6 2.3 0.22 2.87 ns ns 8.0 7.1 28.0 209 1.56 3.00 ns
01/08/07 1235 0.06 0.4 1.9 0.23 2.34 2 U 16 8.2 7.0 28.5 345 1.54 2.88 80 B4
01/08/30 1115 0.02 0.4 0.7 0.12 1.09 1.0 8.4 7.8 7.0 24.4 116 3 106.00 110
01/09/09 1330 0.01 U 0.3 2.7 0.13 3.04 ns ns 8.1 7.1 24.8 213 1.52 2.34 ns
01/09/15 1845 0.01 0.2 2.6 0.13 2.83 ns ns 7.6 7.2 24.0 242 1.54 2.88 ns
01/09/28 1730 0.22 0.8 2.6 0.44 3.37 ns ns 7.7 7.0 18.0 211 1.68 4.60 ns
01/10/04 1310 0.01 U 0.3 2.6 0.28 2.93 27 G4 17 8.3 7.0 16.2 189 1.56 3.00 49
01/10/19 1900 0.20 1.6 2.3 0.15 3.90 ns ns 7.7 7.3 13.3 197 1.58 3.41 ns
Roberson (Robeson) Creek TMDL

01/10/29 1230 0.09 0.7 3.1 0.18 3.84 ns ns 10.1 7.2 10.1 277 1.58 3.42 ns
01/11/07 1230 0.01 0.6 3.8 0.16 4.35 0.8 ns 12.3 7.1 5.5 285 1.7 5.60 33
01/11/14 1145 0.07 0.4 3.2 0.12 3.63 0.2 57 9.4 7.0 5.3 289 1.72 5.90 46 Q
01/12/11 1235 0.02 0.5 4.2 0.26 4.71 2 ns 11.5 7.2 5.8 340 2.14 20.00 2800
02/01/24 1630 0.33 0.8 1.7 0.14 2.49 ns ns 12.4 7.1 5.9 267 1.63 3.81 ns
02/01/31 0930 0.06 0.3 1.4 0.09 1.70 ns ns 12.2 7.0 5.9 199 1.76 6.90 ns
02/02/05 1245 1.0 J3 1.1 2.2 0.14 3.30 1.7G5G1 ns 10.4 7.2 6.4 193 1.76 6.90 60 Q1
02/01/10 1240 0.32 0.7 1.6 0.13 2.26 1.4 G5 ns 16.0 7.0 2.0 201 1.74 6.58 420
02/03/08 1320 .01 U .2 U 0.76 0.08 1 U ns 12.5 7.1 10.8 137 1.78 7.20 34
02/04/15 1140 0.04 0.4 1.2 0.09 1.62 1 ns 12.6 7.6 19.1 162 1.72 5.90 30
02/05/01 1030 0.04 0.6 2 0.14 2.56 ns ns 7.7 7.2 18.0 208 1.64 3.83 240 B4
02/05/02 1830 0.06 0.5 3.2 0.23 3.65 ns ns 7.8 7.2 17.9 217 1.64 3.83 ns
02/05/08 1430 0.04 0.4 1.6 0.17 1.98 ns ns 6.4 7.1 18.2 229 1.58 3.42 ns
02/05/14 0700 0.05 0.3 2.1 0.17 2.36 ns ns ns ns ns ns 1.46 1.62 ns
02/05/29 1830 0.03 0.6 3 0.17 3.58 ns ns ns ns ns ns 1.46 1.62 ns
02/06/26 1045 .01 U 0.7 1.2 0.29 1.85 4 ns 6.9 7.7 24.4 408 1.36 0.32 19
02/07/22 1330 0.02 0.9 2.5 0.34 3.42 ns ns 12.2 8.2 26.5 282 1.36 0.32 ns
02/08/15 1040 .02 U 0.7 1.1 0.22 1.80 ns ns ns ns ns ns 1.60 3.54 ns

RC10 01/05/10 1105 <0.20 <0.6 0.92 0.10 ns Lab 13.7 10.4 27.0 235 ns
Roberson Cr near 01/06/13 1045 0.05 1.0 0.09 0.12 1.08 ns 48 15.2 11.8 30.0 263 1B1,Q ns
Seaforth ramp 01/06/21 1255 0.03 0.7 <0.01 0.13 1.1 32 14.4 10.1 31.2 222 2 25
(#B2450000) 01/07/11 1330 0.76 1.5 0.02 0.05 1.52 ns ns 6.0 7.0 26.0 210 73 51
Lat 35o 42’ 10" 01/08/07 1110 0.02 1.1 0.01 U 0.12 4.0 43 11.1 9.3 30.5 198 6 ns
Long 79o 06’ 05" 01/08/30 1155 0.02 1.0 0.01 U 0.09 0.5 J2 33 11.1 9.3 30.5 198 1 25
01/09/19 1135 0.01 U 1.0 0.01 U 0.10 5.5 J2 46 12.9 9.2 25.5 211 3 Q 24
01/10/05 0920 0.26 1.1 0.12 0.10 1.22 ns ns 10.1 8.9 21.3 228 27 52
01/10/04 1120 0.01 U 1.0 0.07 0.07 1.07 ns 64 10.3 8.7 22.0 230 6 29
01/10/29 1310 0.06 1.3 0.65 0.10 1.95 ns 39 11.0 8.8 21.4 271 na 62
01/10/31 0950 0.22 1.5 0.31 0.10 1.81 ns ns 12.7 8.8 15.8 258 1 B2 Q 65
01/11/08 1120 0.01 1.3 0.06 0.13 1.36 7.7 99 12.8 8.6 15.1 255 1 B2 Q 58
01/12/17 1320 0.20 1.5 0.92 0.21 2.42 ns ns 11.7 8.0 7.1 280 ns 66
02/04/08 1325 0.01 0.7 0.49 0.12 1.16 ns ns 10.7 8.3 16.9 150 41 37
02/04/15 1210 ns ns 9.3 8.8 22.9 107 ns ns
02/04/22 1425 0.03 0.9 0.43 0.08 1.28 ns ns 6.1 9.0 25.0 193 4 Q1 44
02/05/07 1755 0.08 0.6 0.55 0.06 1.10 ns ns 12.8 8.8 22.8 246 ns 32
Roberson (Robeson) Creek TMDL

02/05/08 1410 .01 U 0.6 0.43 0.05 1.01 4.8 ns 11.7 9.2 28.0 258 ns 26
02/06/19 1605 0.02 0.4 0.18 0.10 0.54 ns ns 10.9 8.8 27.6 216 ns 27
02/06/26 1225 0.04 1.4 .01 U 0.06 4.9 ns 5.5 7.6 29.8 360 2 32
02/07/09 1430 0.04 0.6 1.2 0.25 1.75 ns ns 13.1 9.1 30.1 260 ns 69
02/07/29 1415 0.03 0.8 0.02 0.10 0.83 8.7 ns 14.2 9.5 32.4 468 4 78
02/08/15 1215 .02 U 1.5 .02 U 0.11 ns ns 8.1 8.0 31.2 411 ns 78
02/08/28 0950 ns 2.2 7.0 25.8 433

RC11 01/06/13 1035 0.12 1.0 0.16 0.11 1.11 ns 23 15.3 11.7 30.4 243 ns B1,Q 23
Roberson Cr o.5 mi 01/06/21 1245 0.06 1.3 Q 0.01 U 0.08 1.3 32 14.9 10.1 31.6 230 1 24
from Seaforth ramp 01/08/07 1100 0.03 1.2 0.01 U 0.10 2.1 21 13.1 9.5 30.7 202 1
Lat 35o 42’ 12" 01/08/30 1145 0.03 1.0 0.01 U 0.12 1.1 26 13.1 9.5 30.7 202 2
Long 79o 05’ 35" 01/09/19 1145 0.01 U 1.0 0.01 U 0.09 5.6 23 11.3 8.8 25.2 197 9 Q
01/10/04 1110 0.01 U 0.8 0.15 0.06 0.99 ns 64 10.3 8.7 22.0 230 1 24
01/10/29 1320 0.05 1.4 0.72 0.11 2.12 ns 36 A 11.0 8.8 21.4 270 na
01/11/08 1115 0.07 1.4 0.01 0.12 1.41 7.4 91 12.2 8.5 16.0 232 1 Q
02/04/15 1220 ns 9.5 8.7 22.9 107
02/04/22 1415 0.01 0.8 0.41 0.04 1.18 ns ns 5.9 9.3 25.3 208 2 Q1 58
02/05/08 1400 .01 U 0.5 0.53 0.06 1.05 6.6 ns 13.7 9.4 27.0 286 ns 41
02/06/26 1235 .01 U 1.1 .01 U 0.05 4.1 ns 7.4 8.6 29.9 318 3 36
02/07/29 1400 .02 U 0.9 0.5 0.15 1.39 6.0 ns 13.0 9.1 32.3 497 10 62
02/08/15 1200 .02 U 1.6 .02 U 0.14 ns ns 8.1 8.0 32.0 410 ns 66
02/08/28 1000 ns 0.2 6.8 26.9 437

Qualifier Codes:
SYMBOL
DEFINITION
A
Value reported is the mean (average) of two or more determinations. This code is to be used if the results of two or more discrete and
separate samples are averaged. These samples shall have been processed and analyzed independently (e.g. field duplicates,
different dilutions of the same sample).
B
Results based upon colony counts outside the acceptable range and should be used with caution. This code applies to
microbiological tests and specifically to membrane filter (MF) colony counts. It is to be used if less than 100% sample was analyzed
and the colony count is generated from a plate in which the number of coliform colonies exceeds the ideal ranges indicated by the
method. These ideal ranges are defined in the method as:
Roberson (Robeson) Creek TMDL

Fecal coliform bacteria: 20-60 colonies Total coliform bacteria: 20-80 colonies

1.Countable membranes with less than 20 colonies. Reported value is estimated or is a total of the counts on all filters
reported per 100 ml.
2.Counts from all filters were zero. The value reported is based on the number of colonies per 100 ml that would have been
reported if there had been one colony on the filter representing the largest filtration volume (reported as a less than "<"
value).
3.Countable membranes with more than 60 or 80 colonies. The value reported is calculated using the count from the smallest
volume filtered and reported as a greater than ">" value.
4.Filters have counts of both >60 or 80 and <20. Reported value is a total of the counts from all countable filters reported per
100 ml.
5.Too many colonies were present; too numerous to count (TNTC), the numeric value represents the maximum number of
counts typically accepted on a filter membrane (60 for fecal and 80 for total), multiplied by 100 and then divided by the
smallest filtration volume analyzed. This number is reported as a greater than value.
6.Estimated Value. Blank contamination evident.

Note: A "B" value shall be accompanied by justification for its use denoted by the numbers listed above (ex. B1, B2, etc.)
C
Total residual chlorine was present in sample upon receipt in the laboratory; value not accurate (cyanide, phenol, NH3, TKN,
coliform, organics)
G
A single quality control failure occurred during biochemical oxygen demand (BOD) analysis. The sample results should be used with
caution.

1.The dissolved oxygen (DO) depletion of the dilution water blank exceeded 0.2 mg/L.
2.The bacterial seed controls did not meet the requirement of a DO depletion of at least 2.0 mg/L and/or a DO residual of at
least 1.0 mg/L.
3.No sample dilution met the requirement of a DO depletion of at least 2.0 mg/L and/or a DO residual of at least 1.0 mg/L.
4.Evidence of toxicity was present. This is generally characterized by a significant increase in the BOD value as the sample
concentration decreases.
5.The glucose/glutamic acid standard exceeded the range of 198 ± 30.5 mg/L.
6.The calculated seed correction exceeded the range of 0.6 to 1.0 mg/L.
7.Less than 1 mg/L DO remained for all dilutions set. The reported value is an estimated greater than value and is calculated
for the dilution using the least amount of sample.
8.Oxygen usage is less than 2 mg/L for all dilutions set. The reported value is an estimated less than value and is calculated
Roberson (Robeson) Creek TMDL

for the dilution using the most amount of sample.
9.The DO depletion of the dilution water blank produced a negative value.

Note: A "G" value shall be accompanied by justification for its use denoted by the numbers listed above (ex. G1, G2, etc.)
J
Estimated value; value may not be accurate. This code is to be used in the following instances:

1.surrogate recovery limits have been exceeded;
2.the reported value failed to meet the established quality control criteria for either precision or accuracy;
3.the sample matrix interfered with the ability to make any accurate determination; or
4.the data is questionable because of improper laboratory or field protocols (e.g. composite sample was collected instead of
grab, plastic instead of glass container, etc.).
5.temperature limits exceeded (samples frozen or >6° C) during transport, non-reportable for NPDES compliance monitoring.
6.the laboratory analysis was from an unpreserved or improperly chemically preserved sample. The data may not be accurate.
7.This qualifier is used to identify analyte concentration exceeding the upper calibration range of the analytical
instrument/method. The reported value should be considered estimated.

Note: A "J" value shall be accompanied by justification for its use denoted by the numbers listed above (ex. J1, J2, etc.). A "J" value
shall not be used if another code applies (ex. N, V, M).
M
Sample and duplicate results are "out of control". The sample is non-homogenous (e.g. VOA soil). The reported value is the lower
value of duplicate analyses of a sample.
N
Presumptive evidence of presence of material; estimated value. This code is to be used if:

1.The component has been tentatively identified based on mass spectral library search;
2.There is an indication that the analyte is present, but quality control requirements for confirmation were not met (i.e.,
presence of analyte was not confirmed by alternate procedures).
3.This code shall be used if the level is too low to permit accurate quantification, but the estimated concentration is less than
the laboratory practical quantitation limit and greater than the laboratory method detection limit. This code is not routinely
used for most analyses.
Q
Holding time exceeded. These codes shall be used if the value is derived from a sample that was received, prepared and/or
analyzed after the approved holding time restrictions for sample preparation and analysis.

1.Holding time exceeded prior to receipt by lab
Roberson (Robeson) Creek TMDL

2.Holding time exceeded following receipt by lab
S
Not enough sample provided to prepare and/or analyze a method-required matrix spike (MS) and/or duplicate (MSD).
U
Indicates that the analyte was analyzed for but not detected above the reported practical quantitation limit*. The number value
reported with the "U" qualifier is equal to the laboratory’s practical quantitation limit*.
X
Sample not analyzed for this constituent

1.Sample not screened for this compound.
2.Sampled, but analysis lost or not performed-field error
3.Sampled, but analysis lost or not performed-lab error

Note: an "X" value shall be accompanied by justification for its use by the numbers listed.
V
Indicates the analyte was detected in both the sample and the associated method blank. Note: The value in the blank shall not be
subtracted from the associated samples.
Z
The sample results are rejected due to serious deficiencies in the ability to analyze the sample and meet quality control criteria. The
presence or absence of the analyte cannot be verified.
P
Elevated PQL* due to matrix interference and/or sample dilution.
Y
Elevated PQL* due to insufficient sample size

*PQL
The Practical Quantitation Limit (PQL) is defined and proposed as "the lowest level achievable among laboratories within specified
limits during routine laboratory operation". The PQL is about three to five times the calculated Method Detection Limit (MDL) and
represents a practical and routinely achievable detection limit with a relatively good certainty that any reported value is reliable"

Roberson (Robeson) Creek TMDL

Appendix II. DWQ ambient data collected at RC10.

TKN
(mg/L)
NOx
(mg/L)
TP
(mg/L) Chl a (ug/L)TN (mg/L)
1/30/97 0.400 0.740 0.130 1.140
2/27/97 0.400 1.100 0.110 1.500
3/31/97 0.200 0.560 0.100 0.760
5/22/97 0.400 0.580 0.160 0.980
6/30/97 1.000 0.130 0.140 1.130
9/8/97 0.500 0.160 0.080 0.660
9/29/97 0.600 0.770 0.210 1.370
10/15/97 0.600 0.310 0.230 0.910
11/17/97 0.300 1.100 0.200 1.400
12/11/97 0.400 1.500 0.270 1.900
1/14/98 0.500 0.580 0.130 1.080
2/11/98 0.600 0.730 0.160 1.330
3/3/98 0.300 0.580 0.100 0.880
4/15/98 0.400 0.490 0.130 0.890
5/27/98 0.200 0.420 0.020 40 0.620
6/11/98 0.300 0.260 0.080 18 0.560
7/29/98 0.500 0.010 0.080 26 0.510
8/31/98 0.600 0.030 0.110 58 0.630
9/28/98 0.400 0.010 0.120 0.410
10/28/98 0.500 0.120 0.090 50 0.620
11/29/98 0.600 0.910 0.140 11 1.510
12/28/98 1.000 1.100 0.290 5 2.100
1/28/99 0.600 0.530 0.120 1.130
2/17/99 0.400 1.000 0.090 7 1.400
3/23/99 0.400 0.670 0.150 1.070
4/29/99 0.400 0.620 0.090 1.020
5/24/99 0.400 0.310 0.100 51 0.710
6/24/99 0.900 0.300 0.170 1.200
7/27/99 1.100 0.170 0.140 98 1.270
Roberson (Robeson) Creek TMDL

8/17/99 0.600 0.010 0.110 39 0.610
9/29/99 0.400 0.270 0.160 0.670
10/18/99 0.600 0.500 0.180 1.100
11/2/99 0.500 0.240 0.140 0.740
12/2/99 0.400 0.680 0.140 1.080
2/14/00 0.400 0.440 0.180 0.840
3/15/00 0.400 0.480 0.070 0.880
4/26/00 0.500 0.500 0.070 1.000
5/22/00 0.400 0.090 0.080 19 0.490
6/14/00 0.700 0.030 0.090 0.730
8/30/00 0.700 0.550 0.170 64 1.250
9/13/00 0.600 0.110 0.140 140 0.710
10/9/00 0.600 0.300 0.080 24 0.900
11/29/00 0.700 0.300 0.160 1.000
1/3/01 0.500 1.300 0.140 1.800
2/1/01 1.000 1.400 0.500 2.400
5/21/01 0.600 1.300 0.100 31 1.900
6/25/01 0.980 0.010 0.070 10 0.990
7/11/01 1.500 0.020 0.050 51 1.520
10/5/01 1.100 0.120 0.100 52 1.220
10/31/01 1.500 0.310 0.100 65 1.810
11/29/01 0.550 1.800 0.040 5 2.350
12/17/01 1.500 0.920 0.210 66 2.420
1/14/02 3.600 1.200 0.170 3 4.800
2/19/02 0.940 1.500 0.090 3 2.440
3/7/02 0.290 0.570 0.060 2 0.860
4/8/02 0.670 0.490 0.120 37 1.160
5/7/02 0.550 0.550 0.060 32 1.100
6/19/02 0.360 0.180 0.100 27 0.540
7/10/02 0.640 0.990 0.150 3 1.630
9/10/02 0.660 0.350 0.060 30 1.010

Roberson (Robeson) Creek TMDL

Appendix III. Water column profile data for the Roberson Creek Cove.

Station # & Location
Sample
Date Time Depth (meters)DO pH Temp Cond Secchi a
yy/mm/dd mg/L units C umhos meters ug/L
Roberson Cr near 01/06/13 1045 0.1 15.2 11.8 30.0 263 ns
Seaforth ramp 01/06/21 1255 0.1 14.4 10.1 31.2 222 25
(#B2450000) 01/07/11 1330 0.1 6.0 7.0 26.0 210 51
Lat 35o 42’ 10" 01/08/07 1110 0.1 11.1 9.3 30.5 198 ns
Long 79o 06’ 05" 01/08/30 1155 0.1 11.1 9.3 30.5 198 25
01/09/19 1135 0.1 12.9 9.2 25.5 211 0.35 24
01/09/19 1135 1 12.6 9.1 24.8 212
01/09/19 1135 2 10.7 7.7 24.2 217
01/09/19 1135 3 8.7 8.0 22.6 210
01/09/19 1135 3.5 8.7 8.0 22.6 210
01/10/05 0920 0.1 10.1 8.9 21.3 228 52
01/10/04 1120 0.1 10.3 8.7 22.0 230 29
01/10/29 1310 0.1 11.0 8.8 21.4 271 62
01/10/31 0950 0.1 12.7 8.8 15.8 258 65
01/11/08 1120 0.1 12.8 8.6 15.1 255 0.50 58
01/11/08 1120 1 11.3 8.3 13.3 253
01/11/08 1120 2 9.7 7.5 12.2 255
01/11/08 1120 2.5 9.7 7.4 11.1 265
01/12/17 1320 0.1 11.7 8.0 7.1 280 66
01/04/08 1325 0.1 10.7 8.3 16.9 150 0.35 37
02/04/15 1210 0.1 9.3 8.8 22.9 107 ns
02/04/15 1210 1 9.1 8.6 22.8 106
02/04/15 1210 2 8.8 8.0 22.0 106
02/04/15 1210 3 7.6 7.9 21.2 107
02/04/15 1210 3.3 7.1 7.8 18.6 111
02/04/22 1425 0.1 6.1 9.0 25.0 193 0.30 44
02/04/22 1425 1 6.0 8.2 24.5 194
02/04/22 1425 2 5.6 7.8 24.0 193
Roberson (Robeson) Creek TMDL

02/04/22 1425 3 5.5 7.7 22.8 193
02/04/22 1425 3.5 5.2 7.4 21.3 196
02/05/07 1755 0.1 12.8 8.8 22.8 246 32
02/05/08 1410 0.1 11.7 9.2 28.0 258 0.30 26
02/05/08 1410 1 12.0 9.0 24.5 255
02/05/08 1410 2 11.4 8.8 23.5 256
02/05/08 1410 2.5 8.4 7.5 22.6 255
02/06/19 1605 0.1 10.9 8.8 27.6 216 27
02/06/26 1225 0.1 5.5 7.6 29.8 360 32
02/07/09 1430 0.1 13.1 9.1 30.1 260 69
02/07/29 1415 0.1 14.2 9.5 32.4 468 0.30 78
02/07/29 1415 1 6.5 8.6 29.3 470
02/07/29 1415 2 6.1 8.7 28.4 474
02/08/15 1215 0.1 8.1 8.0 31.2 411 78
02/08/28 0950 0.1 2.2 7.0 25.8 433 0.45
02/08/28 0950 1 2.2 6.8 25.6 426
02/08/28 0950 1.4 1.6 6.8 25.1 417

RC11 01/06/13 1035 0.1 15.3 11.7 30.4 243 23
Roberson Cr o.5 mi 01/06/21 1245 0.1 14.9 10.1 31.6 230 24
from Seaforth ramp 01/08/07 1100 0.1 13.1 9.5 30.7 202
Lat 35o 42’ 12" 01/08/30 1145 0.1 13.1 9.5 30.7 202
Long 79o 05’ 35" 01/09/19 1145 0.1 11.3 8.8 25.2 197 0.45
01/09/19 1145 1 10.1 8.7 24.9 198
01/09/19 1145 2 9.1 8.4 24.5 197
01/09/19 1145 3 8.9 8.3 24.5 198
01/09/19 1145 4 8.5 7.9 24.2 212
01/09/19 1145 5 6.8 7.4 23.8 218
01/09/19 1145 6 3.8 7.0 23.0 226
Roberson (Robeson) Creek TMDL

01/10/04 1110 0.1 10.3 8.7 22.0 230 24
01/10/29 1320 0.1 11.0 8.8 21.4 270
01/11/08 1115 0.1 12.2 8.5 16.0 232 0.50
01/11/08 1115 1 11.4 8.4 15.1 237
01/11/08 1115 2 10.8 8.2 14.9 236
01/11/08 1115 3 10.1 7.8 14.6 251
01/11/08 1115 4 9.7 7.6 14.2 254
01/11/08 1115 5 9.1 7.3 13.5 255
01/11/08 1115 6 7.3 7.0 13.2 322
02/04/15 1220 0.1 9.5 8.7 22.9 107 0.40
02/04/15 1220 1 9.1 8.6 22.6 107
02/04/15 1220 2 8.7 8.0 22.1 107
02/04/15 1220 3 8.2 8.0 21.3 106
02/04/15 1220 5 6.5 7.2 19.9 107
02/04/15 1220 5 6.5 7.2 19.8 110
02/04/22 1415 0.1 5.9 9.3 25.3 208 0.30 58
02/04/22 1415 1 5.7 8.8 25.2 207
02/04/22 1415 2 5.3 8.6 24.9 208
02/04/22 1415 3 5.3 8.0 24.0 207
02/04/22 1415 4 5.0 7.5 23.5 207
02/04/22 1415 4.6 5.0 7.5 23.5 209
02/05/08 1400 0.1 13.7 9.4 27.0 286 0.30 41
02/05/08 1400 1 13.3 9.2 23.9 259
02/05/08 1400 2 10.1 8.0 22.5 262
02/05/08 1400 3 7.3 7.3 21.3 265
02/06/26 1235 0.1 7.4 8.6 29.9 318 36
02/07/29 1400 0.1 13.0 9.1 32.3 497 0.35 62
02/07/29 1400 1 6.7 8.5 30.2 549
02/07/29 1400 2 5.0 8.3 29.0 594
02/08/15 1200 0.1 8.1 8.0 32.0 410 66
02/08/28 1000 0.1 0.2 6.8 26.9 437
02/08/28 1000 1 0.2 6.8 26.9 436 0.60
Roberson (Robeson) Creek TMDL

02/08/28 1000 2 0.15 6.8 26.9 436
02/08/28 1000 3 0.14 6.8 26.6 530
02/08/28 1000 4 1.14 7 26.2 641
02/08/28 1000 4.5 2.73 6.9 26.1 674

Roberson (Robeson) Creek TMDL

Appendix IV. Stream flow inputs for FLUX.

Flows in cfs Estimated Roberson Creek Flow at RC8 using DA ratio
Estimated Roberson Ck. (RC8) plus WWTP
Flow
DATE Rocky River Flow Tick Creek F --using Tick Creek --using Rocky River Pittsboro wwtp flow --using Tick Creek --using Rocky River
04/01/01 62 133 211.47 205.84 2.0336 213.5036 207.8736
04/02/01 31 45 71.55 102.92 1.2927 72.8427 104.2127
04/03/01 12 23 36.57 39.84 1.10515 37.67515 40.94515
04/04/01 8.5 18 28.62 28.22 0.9641 29.5841 29.1841
04/05/01 6.6 13 20.67 21.912 0.9734 21.6434 22.8854
04/06/01 5.8 10 15.9 19.256 0.97495 16.87495 20.23095
04/07/01 5.3 8.9 14.151 17.596 0.95635 15.10735 18.55235
04/08/01 5 7.6 12.084 16.6 0.96565 13.04965 17.56565
04/09/01 4.5 6.6 10.494 14.94 0.94395 11.43795 15.88395
04/10/01 3.9 5.8 9.222 12.948 0.9083 10.1303 13.8563
04/11/01 3.4 5.1 8.109 11.288 0.92845 9.03745 12.21645
04/12/01 3.1 5 7.95 10.292 0.93 8.88 11.222
04/13/01 3 4.6 7.314 9.96 0.775 8.089 10.735
04/14/01 2.9 4.3 6.837 9.628 0.7564 7.5934 10.3844
04/15/01 2.7 4.1 6.519 8.964 0.7099 7.2289 9.6739
04/16/01 2.7 4 6.36 8.964 0.7037 7.0637 9.6677
04/17/01 2.4 3.1 4.929 7.968 0.4867 5.4157 8.4547
04/18/01 2.5 2.9 4.611 8.3 0.73005 5.34105 9.03005
04/19/01 2.3 2.8 4.452 7.636 0.73315 5.18515 8.36915
04/20/01 2.3 3 4.77 7.636 0.71455 5.48455 8.35055
04/21/01 2.3 3 4.77 7.636 0.73935 5.50935 8.37535
04/22/01 2.3 3.2 5.088 7.636 0.7657 5.8537 8.4017
04/23/01 2.2 3.4 5.406 7.304 0.78895 6.19495 8.09295
04/24/01 2.1 3.7 5.883 6.972 0.84785 6.73085 7.81985
04/25/01 7.7 5.2 8.268 25.564 0.7967 9.0647 26.3607
04/26/01 3.9 5.6 8.904 12.948 0.76415 9.66815 13.71215
04/27/01 2.8 3.7 5.883 9.296 0.7285 6.6115 10.0245
04/28/01 2.4 2.7 4.293 7.968 0.7595 5.0525 8.7275
Roberson (Robeson) Creek TMDL

04/29/01 2 2.5 3.975 6.64 0.62 4.595 7.26
04/30/01 1.9 2 3.18 6.308 0.69595 3.87595 7.00395
05/01/01 1.8 1.3 2.067 5.976 0.7688 2.8358 6.7448
05/02/01 1.8 1.3 2.067 5.976 0.51925 2.58625 6.49525
05/03/01 1.7 1.2 1.908 5.644 0.43555 2.34355 6.07955
05/04/01 1.5 1.1 1.749 4.98 0.42935 2.17835 5.40935
05/05/01 1.4 0.94 1.4946 4.648 0.4154 1.91 5.0634
05/06/01 1.3 0.78 1.2402 4.316 0.4557 1.6959 4.7717
05/07/01 1.3 0.64 1.0176 4.316 0.73315 1.75075 5.04915
05/08/01 1.3 0.59 0.9381 4.316 0.72695 1.66505 5.04295
05/09/01 1.2 0.58 0.9222 3.984 0.72695 1.64915 4.71095
05/10/01 1.3 0.48 0.7632 4.316 0.6758 1.439 4.9918
05/11/01 1.2 0.43 0.6837 3.984 0.69285 1.37655 4.67685
05/12/01 1.3 0.43 0.6837 4.316 0.6944 1.3781 5.0104
05/13/01 1.2 0.6 0.954 3.984 0.6758 1.6298 4.6598
05/14/01 1.1 0.42 0.6678 3.652 0.7285 1.3963 4.3805
05/15/01 1 0.31 0.4929 3.32 0.93 1.4229 4.25
05/16/01 1.7 0.34 0.5406 5.644 0.94395 1.48455 6.58795
05/17/01 2 0.48 0.7632 6.64 0.8153 1.5785 7.4553
05/18/01 1.6 0.54 0.8586 5.312 0.80135 1.65995 6.11335
05/19/01 1.4 0.63 1.0017 4.648 0.7595 1.7612 5.4075
05/20/01 1.3 0.7 1.113 4.316 0.77965 1.89265 5.09565
05/21/01 3 0.7 1.113 9.96 0.82925 1.94225 10.78925
05/22/01 1.5 0.86 1.3674 4.98 0.87265 2.24005 5.85265
05/23/01 1.6 1.5 2.385 5.312 0.72385 3.10885 6.03585
05/24/01 1.1 1.1 1.749 3.652 0.837 2.586 4.489
05/25/01 0.98 0.62 0.9858 3.2536 0.7905 1.7763 4.0441
05/26/01 3.3 1.9 3.021 10.956 0.73315 3.75415 11.68915
05/27/01 2.3 1.9 3.021 7.636 0.7006 3.7216 8.3366
05/28/01 1.5 1.6 2.544 4.98 0.81685 3.36085 5.79685
05/29/01 1.8 1.7 2.703 5.976 0.81995 3.52295 6.79595
05/30/01 1.3 1.5 2.385 4.316 0.7688 3.1538 5.0848
Roberson (Robeson) Creek TMDL

05/31/01 1.2 1.3 2.067 3.984 0.7533 2.8203 4.7373
06/01/01 9.2 39 62.01 30.544 1.47095 63.48095 32.01495
06/02/01 5.2 24 38.16 17.264 1.10515 39.26515 18.36915
06/03/01 2.6 6.5 10.335 8.632 0.61845 10.95345 9.25045
06/04/01 2.4 3.5 5.565 7.968 0.5983 6.1633 8.5663
06/05/01 1.5 2.4 3.816 4.98 0.5425 4.3585 5.5225
06/06/01 1.1 1.6 2.544 3.652 0.7316 3.2756 4.3836
06/07/01 0.93 1.2 1.908 3.0876 0.4898 2.3978 3.5774
06/08/01 2.3 1.4 2.226 7.636 0.50685 2.73285 8.14285
06/09/01 2.1 2.2 3.498 6.972 0.44795 3.94595 7.41995
06/10/01 1 1.7 2.703 3.32 0.46345 3.16645 3.78345
06/11/01 0.89 1.2 1.908 2.9548 0.45415 2.36215 3.40895
06/12/01 0.84 0.97 1.5423 2.7888 0.51305 2.05535 3.30185
06/13/01 4.3 0.91 1.4469 14.276 0.8525 2.2994 15.1285
06/14/01 13 1.6 2.544 43.16 0.88195 3.42595 44.04195
06/15/01 5.1 2.1 3.339 16.932 0.59985 3.93885 17.53185
06/16/01 2.5 2.6 4.134 8.3 0.5859 4.7199 8.8859
06/17/01 2.1 2.5 3.975 6.972 0.527 4.502 7.499
06/18/01 1.4 1.9 3.021 4.648 0.52545 3.54645 5.17345
06/19/01 0.89 1.5 2.385 2.9548 0.42315 2.80815 3.37795
06/20/01 0.78 1.3 2.067 2.5896 0.55335 2.62035 3.14295
06/21/01 0.66 1.3 2.067 2.1912 0.50065 2.56765 2.69185
06/22/01 2.7 4.9 7.791 8.964 1.3485 9.1395 10.3125
06/23/01 13 22 34.98 43.16 0.75175 35.73175 43.91175
06/24/01 2.4 4.7 7.473 7.968 0.8866 8.3596 8.8546
06/25/01 1.6 2.5 3.975 5.312 0.86335 4.83835 6.17535
06/26/01 1.4 3.5 5.565 4.648 0.73315 6.29815 5.38115
06/27/01 1 1.7 2.703 3.32 0.65875 3.36175 3.97875
06/28/01 0.9 1.2 1.908 2.988 0.6231 2.5311 3.6111
06/29/01 0.8 0.94 1.4946 2.656 0.6014 2.096 3.2574
06/30/01 0.81 0.75 1.1925 2.6892 0.5642 1.7567 3.2534
07/01/01 0.65 0.62 0.9858 2.158 0.6169 1.6027 2.7749
Roberson (Robeson) Creek TMDL

07/02/01 0.83 0.48 0.7632 2.7556 0.5487 1.3119 3.3043
07/03/01 0.72 0.38 0.6042 2.3904 0.5115 1.1157 2.9019
07/04/01 1 26 41.34 3.32 2.1173 43.4573 5.4373
07/05/01 5.4 65 103.35 17.928 1.085 104.435 19.013
07/06/01 1.2 4.8 7.632 3.984 0.7657 8.3977 4.7497
07/07/01 0.81 2 3.18 2.6892 0.66495 3.84495 3.35415
07/08/01 2 6.6 10.494 6.64 0.74555 11.23955 7.38555
07/09/01 2.3 4.3 6.837 7.636 0.89745 7.73445 8.53345
07/10/01 1.5 2.3 3.657 4.98 0.7161 4.3731 5.6961
07/11/01 0.99 1.7 2.703 3.2868 0.63395 3.33695 3.92075
07/12/01 0.77 1.8 2.862 2.5564 0.60295 3.46495 3.15935
07/13/01 0.59 1.3 2.067 1.9588 0.5425 2.6095 2.5013
07/14/01 0.55 0.98 1.5582 1.826 0.50685 2.06505 2.33285
07/15/01 0.51 0.7 1.113 1.6932 0.4991 1.6121 2.1923
07/16/01 0.46 0.5 0.795 1.5272 0.48205 1.27705 2.00925
07/17/01 0.42 0.37 0.5883 1.3944 0.48515 1.07345 1.87955
07/18/01 0.5 0.29 0.4611 1.66 0.4712 0.9323 2.1312
07/19/01 0.61 0.28 0.4452 2.0252 0.46965 0.91485 2.49485
07/20/01 0.5 0.25 0.3975 1.66 0.42315 0.82065 2.08315
07/21/01 0.41 0.2 0.318 1.3612 0.3937 0.7117 1.7549
07/22/01 0.38 0.15 0.2385 1.2616 0.41385 0.65235 1.67545
07/23/01 0.31 0.13 0.2067 1.0292 0.49445 0.70115 1.52365
07/24/01 0.34 0.12 0.1908 1.1288 0.59365 0.78445 1.72245
07/25/01 0.48 0.12 0.1908 1.5936 0.75175 0.94255 2.34535
07/26/01 0.82 0.15 0.2385 2.7224 0.496 0.7345 3.2184
07/27/01 2.3 0.21 0.3339 7.636 0.7781 1.112 8.4141
07/28/01 1.6 0.32 0.5088 5.312 0.527 1.0358 5.839
07/29/01 0.78 0.27 0.4293 2.5896 0.50685 0.93615 3.09645
07/30/01 1.7 0.43 0.6837 5.644 0.50375 1.18745 6.14775
07/31/01 1.1 0.27 0.4293 3.652 0.4898 0.9191 4.1418
08/01/01 0.62 0.16 0.2544 2.0584 0.465 0.7194 2.5234
08/02/01 0.55 0.11 0.1749 1.826 0.46035 0.63525 2.28635
Roberson (Robeson) Creek TMDL

08/03/01 0.5 0.09 0.1431 1.66 0.45105 0.59415 2.11105
08/04/01 0.43 0.08 0.1272 1.4276 0.42005 0.54725 1.84765
08/05/01 0.36 0.06 0.0954 1.1952 0.43555 0.53095 1.63075
08/06/01 0.32 0.05 0.0795 1.0624 0.4681 0.5476 1.5305
08/07/01 0.27 0.05 0.0795 0.8964 0.4619 0.5414 1.3583
08/08/01 0.27 0.04 0.0636 0.8964 0.4588 0.5224 1.3552
08/09/01 0.23 0.04 0.0636 0.7636 0.3782 0.4418 1.1418
08/10/01 0.22 0.21 0.3339 0.7304 0.37975 0.71365 1.11015
08/11/01 0.84 7.6 12.084 2.7888 1.4353 13.5193 4.2241
08/12/01 7.5 2.2 3.498 24.9 1.91425 5.41225 26.81425
08/13/01 1.3 0.91 1.4469 4.316 0.9114 2.3583 5.2274
08/14/01 1.1 0.5 0.795 3.652 0.50685 1.30185 4.15885
08/15/01 0.87 0.34 0.5406 2.8884 0.39525 0.93585 3.28365
08/16/01 0.47 0.36 0.5724 1.5604 0.3937 0.9661 1.9541
08/17/01 0.33 0.25 0.3975 1.0956 0.3565 0.754 1.4521
08/18/01 1.1 3.6 5.724 3.652 0.3441 6.0681 3.9961
08/19/01 4.8 6.6 10.494 15.936 0.36115 10.85515 16.29715
08/20/01 1.1 2.1 3.339 3.652 0.33325 3.67225 3.98525
08/21/01 0.58 0.99 1.5741 1.9256 0.30845 1.88255 2.23405
08/22/01 0.4 0.52 0.8268 1.328 0.31 1.1368 1.638
08/23/01 0.35 0.31 0.4929 1.162 0.3193 0.8122 1.4813
08/24/01 2 3.9 6.201 6.64 0.3255 6.5265 6.9655
08/25/01 0.89 2.2 3.498 2.9548 0.32395 3.82195 3.27875
08/26/01 0.42 0.97 1.5423 1.3944 0.3317 1.874 1.7261
08/27/01 0.28 0.55 0.8745 0.9296 0.3689 1.2434 1.2985
08/28/01 0.24 0.39 0.6201 0.7968 0.4309 1.051 1.2277
08/29/01 0.22 0.27 0.4293 0.7304 0.39525 0.82455 1.12565
08/30/01 0.25 22 34.98 0.83 0.3596 35.3396 1.1896
08/31/01 0.48 67 106.53 1.5936 1.39655 107.92655 2.99015
09/01/01 0.3 7.3 11.607 0.996 0.93 12.537 1.926
09/02/01 0.35 4.4 6.996 1.162 0.7471 7.7431 1.9091
09/03/01 0.28 2.7 4.293 0.9296 0.35805 4.65105 1.28765
Roberson (Robeson) Creek TMDL

09/04/01 0.33 2.3 3.657 1.0956 0.34565 4.00265 1.44125
09/05/01 0.35 2 3.18 1.162 0.39835 3.57835 1.56035
09/06/01 0.25 1.5 2.385 0.83 0.4154 2.8004 1.2454
09/07/01 0.22 1.1 1.749 0.7304 0.42005 2.16905 1.15045
09/08/01 0.19 0.85 1.3515 0.6308 0.3472 1.6987 0.978
09/09/01 0.16 0.67 1.0653 0.5312 0.3596 1.4249 0.8908
09/10/01 0.16 0.57 0.9063 0.5312 0.41075 1.31705 0.94195
09/11/01 0.16 0.47 0.7473 0.5312 0.33015 1.07745 0.86135
09/12/01 0.13 0.36 0.5724 0.4316 0.35495 0.92735 0.78655
09/13/01 0.11 0.36 0.5724 0.3652 0.3007 0.8731 0.6659
09/14/01 0.12 0.29 0.4611 0.3984 0.41385 0.87495 0.81225
09/15/01 0.13 0.21 0.3339 0.4316 0.2232 0.5571 0.6548
09/16/01 0.12 0.19 0.3021 0.3984 0.21235 0.51445 0.61075
09/17/01 0.12 0.18 0.2862 0.3984 0.22475 0.51095 0.62315
09/18/01 0.11 0.16 0.2544 0.3652 0.37975 0.63415 0.74495
09/19/01 0.1 0.14 0.2226 0.332 0.3317 0.5543 0.6637
09/20/01 0.11 0.18 0.2862 0.3652 0.33325 0.61945 0.69845
09/21/01 1.2 0.37 0.5883 3.984 0.32395 0.91225 4.30795
09/22/01 0.3 0.46 0.7314 0.996 0.20615 0.93755 1.20215
09/23/01 0.14 0.13 0.2067 0.4648 0.2604 0.4671 0.7252
09/24/01 0.17 1.8 2.862 0.5644 0.60295 3.46495 1.16735
09/25/01 1.3 1.2 1.908 4.316 0.3565 2.2645 4.6725
09/26/01 0.26 0.63 1.0017 0.8632 0.24955 1.25125 1.11275
09/27/01 0.13 0.38 0.6042 0.4316 0.248 0.8522 0.6796
09/28/01 0.13 0.29 0.4611 0.4316 0.2263 0.6874 0.6579
09/29/01 0.12 0.21 0.3339 0.3984 0.2449 0.5788 0.6433
09/30/01 0.1 0.16 0.2544 0.332 0.2666 0.521 0.5986
10/01/01 0.1 0.14 0.2226 0.332 0.3348 0.5574 0.6668
10/02/01 0.11 0.12 0.1908 0.3652 0.2418 0.4326 0.607
10/03/01 0.13 0.11 0.1749 0.4316 0.341 0.5159 0.7726
10/04/01 0.17 0.1 0.159 0.5644 0.2232 0.3822 0.7876
10/05/01 0.18 0.08 0.1272 0.5976 0.2821 0.4093 0.8797
Roberson (Robeson) Creek TMDL

10/06/01 0.26 0.1 0.159 0.8632 0.2573 0.4163 1.1205
10/07/01 0.33 0.14 0.2226 1.0956 0.3193 0.5419 1.4149
10/08/01 0.22 0.13 0.2067 0.7304 0.26505 0.47175 0.99545
10/09/01 0.22 0.09 0.1431 0.7304 0.2542 0.3973 0.9846
10/10/01 0.23 0.05 0.0795 0.7636 0.2883 0.3678 1.0519
10/11/01 0.22 0.05 0.0795 0.7304 0.1984 0.2779 0.9288
10/12/01 0.1 0.06 0.0954 0.332 0.4774 0.5728 0.8094
10/13/01 0.12 0.17 0.2703 0.3984 0.35185 0.62215 0.75025
10/14/01 0.22 1.1 1.749 0.7304 0.29605 2.04505 1.02645
10/15/01 1.7 2.2 3.498 5.644 0.279 3.777 5.923
10/16/01 0.33 0.7 1.113 1.0956 0.30225 1.41525 1.39785
10/17/01 0.22 0.83 1.3197 0.7304 0.30845 1.62815 1.03885
10/18/01 0.13 0.67 1.0653 0.4316 0.3286 1.3939 0.7602
10/19/01 0.11 0.59 0.9381 0.3652 0.3007 1.2388 0.6659
10/20/01 0.12 0.67 1.0653 0.3984 0.26505 1.33035 0.66345
10/21/01 0.12 0.63 1.0017 0.3984 0.2418 1.2435 0.6402
10/22/01 0.12 0.53 0.8427 0.3984 0.26505 1.10775 0.66345
10/23/01 0.12 0.61 0.9699 0.3984 0.34255 1.31245 0.74095
10/24/01 0.12 1.2 1.908 0.3984 0.37665 2.28465 0.77505
10/25/01 0.13 1.1 1.749 0.4316 0.3627 2.1117 0.7943
10/26/01 0.12 0.7 1.113 0.3984 0.3348 1.4478 0.7332
10/27/01 0.13 0.42 0.6678 0.4316 0.248 0.9158 0.6796
10/28/01 0.13 0.2 0.318 0.4316 0.186 0.504 0.6176
10/29/01 0.12 0.17 0.2703 0.3984 0.28675 0.55705 0.68515
10/30/01 0.11 0.16 0.2544 0.3652 0.29605 0.55045 0.66125
10/31/01 0.11 0.14 0.2226 0.3652 0.3317 0.5543 0.6969

04/01/02 11 73 116.07 36.52 0.9951 117.0651 37.5151
04/02/02 4.7 18 28.62 15.604 0.682 29.302 16.286
04/03/02 3.1 11 17.49 10.292 0.6107 18.1007 10.9027
04/04/02 2.5 7.2 11.448 8.3 0.55025 11.99825 8.85025
04/05/02 2 5.6 8.904 6.64 0.52855 9.43255 7.16855
Roberson (Robeson) Creek TMDL

04/06/02 1.9 4.8 7.632 6.308 0.5115 8.1435 6.8195
04/07/02 1.8 4.1 6.519 5.976 0.48515 7.00415 6.46115
04/08/02 1.9 3.6 5.724 6.308 0.50685 6.23085 6.81485
04/09/02 1.9 3.7 5.883 6.308 0.54405 6.42705 6.85205
04/10/02 3.9 4.4 6.996 12.948 0.58435 7.58035 13.53235
04/11/02 1.8 3.9 6.201 5.976 0.51305 6.71405 6.48905
04/12/02 1.5 3.4 5.406 4.98 0.5115 5.9175 5.4915
04/13/02 1.7 4.1 6.519 5.644 0.65255 7.17155 6.29655
04/14/02 1.4 3.1 4.929 4.648 0.62775 5.55675 5.27575
04/15/02 1.3 2.8 4.452 4.316 0.5394 4.9914 4.8554
04/16/02 1.2 2.3 3.657 3.984 0.6758 4.3328 4.6598
04/17/02 1.1 2.1 3.339 3.652 0.4557 3.7947 4.1077
04/18/02 0.99 1.9 3.021 3.2868 0.38905 3.41005 3.67585
04/19/02 0.92 1.7 2.703 3.0544 0.54405 3.24705 3.59845
04/20/02 0.9 1.6 2.544 2.988 0.4216 2.9656 3.4096
04/21/02 0.86 1.5 2.385 2.8552 0.43865 2.82365 3.29385
04/22/02 0.85 1.3 2.067 2.822 0.47585 2.54285 3.29785
04/23/02 0.66 1.1 1.749 2.1912 0.46345 2.21245 2.65465
04/24/02 0.6 1 1.59 1.992 0.45725 2.04725 2.44925
04/25/02 0.7 0.94 1.4946 2.324 0.465 1.9596 2.789
04/26/02 0.64 1 1.59 2.1248 0.46035 2.05035 2.58515
04/27/02 0.55 0.9 1.431 1.826 0.51305 1.94405 2.33905
04/28/02 0.6 0.84 1.3356 1.992 0.31 1.6456 2.302
04/29/02 0.57 1.2 1.908 1.8924 0.44795 2.35595 2.34035
04/30/02 0.53 1.2 1.908 1.7596 0.4371 2.3451 2.1967
05/01/02 0.53 1.1 1.749 1.7596 0.4371 2.1861 2.1967
05/02/02 0.66 0.72 1.1448 2.1912 0.45105 1.59585 2.64225
05/03/02 0.67 0.92 1.4628 2.2244 0.4123 1.8751 2.6367
05/04/02 1 1.1 1.749 3.32 0.43555 2.18455 3.75555
05/05/02 1.4 1.2 1.908 4.648 0.4216 2.3296 5.0696
05/06/02 0.81 1.2 1.908 2.6892 0.4278 2.3358 3.117
05/07/02 0.66 0.74 1.1766 2.1912 0.4278 1.6044 2.619
Roberson (Robeson) Creek TMDL

05/08/02 0.53 0.51 0.8109 1.7596 0.45725 1.26815 2.21685
05/09/02 0.54 0.38 0.6042 1.7928 0.3968 1.001 2.1896
05/10/02 0.46 0.28 0.4452 1.5272 0.3906 0.8358 1.9178
05/11/02 0.41 0.19 0.3021 1.3612 0.3689 0.671 1.7301
05/12/02 0.37 0.17 0.2703 1.2284 0.3286 0.5989 1.557
05/13/02 0.42 0.18 0.2862 1.3944 0.3286 0.6148 1.723
05/14/02 0.64 0.24 0.3816 2.1248 0.40455 0.78615 2.52935
05/15/02 0.67 0.22 0.3498 2.2244 0.30535 0.65515 2.52975
05/16/02 0.53 0.27 0.4293 1.7596 0.31155 0.74085 2.07115
05/17/02 0.44 0.3 0.477 1.4608 0.30845 0.78545 1.76925
05/18/02 0.83 0.17 0.2703 2.7556 0.2387 0.509 2.9943
05/19/02 1.1 0.16 0.2544 3.652 0.51305 0.76745 4.16505
05/20/02 0.57 0.16 0.2544 1.8924 0.32705 0.58145 2.21945
05/21/02 0.41 0.14 0.2226 1.3612 0.3937 0.6163 1.7549
05/22/02 0.33 0.06 0.0954 1.0956 0.3937 0.4891 1.4893
05/23/02 0.36 0.05 0.0795 1.1952 0.37045 0.44995 1.56565
05/24/02 0.27 0.05 0.0795 0.8964 0.35805 0.43755 1.25445
05/25/02 0.22 0.05 0.0795 0.7304 0.34565 0.42515 1.07605
05/26/02 0.21 0.04 0.0636 0.6972 0.2976 0.3612 0.9948
05/27/02 0.17 0.03 0.0477 0.5644 0.27745 0.32515 0.84185
05/28/02 0.2 0.03 0.0477 0.664 0.30535 0.35305 0.96935
05/29/02 0.14 0.04 0.0636 0.4648 0.3348 0.3984 0.7996
05/30/02 0.22 0.03 0.0477 0.7304 0.372 0.4197 1.1024
05/31/02 0.34 0.03 0.0477 1.1288 0.40455 0.45225 1.53335
06/01/02 0.32 0.03 0.0477 1.0624 0.3348 0.3825 1.3972
06/02/02 0.2 0.03 0.0477 0.664 0.31465 0.36235 0.97865
06/03/02 0.21 0.04 0.0636 0.6972 0.3317 0.3953 1.0289
06/04/02 0.12 0.03 0.0477 0.3984 0.33945 0.38715 0.73785
06/05/02 0.13 0.02 0.0318 0.4316 0.34565 0.37745 0.77725
06/06/02 0.12 0.02 0.0318 0.3984 0.5177 0.5495 0.9161
06/07/02 0.1 0.04 0.0636 0.332 0.50065 0.56425 0.83265
06/08/02 0.16 0.03 0.0477 0.5312 0.35185 0.39955 0.88305
Roberson (Robeson) Creek TMDL

06/09/02 0.12 0.02 0.0318 0.3984 0.2976 0.3294 0.696
06/10/02 0.13 0.02 0.0318 0.4316 0.33325 0.36505 0.76485
06/11/02 0.08 0.01 0.0159 0.2656 0.32705 0.34295 0.59265
06/12/02 0.08 0.01 0.0159 0.2656 0.32705 0.34295 0.59265
06/13/02 0.08 0.01 0.0159 0.2656 0.32705 0.34295 0.59265
06/14/02 0.06 0.01 0.0159 0.1992 0.34255 0.35845 0.54175
06/15/02 0.1 0 0 0.332 0.31155 0.31155 0.64355
06/16/02 0.07 0 0 0.2324 0.28675 0.28675 0.51915
06/17/02 0.04 0 0 0.1328 0.32705 0.32705 0.45985
06/18/02 0.03 0 0 0.0996 0.3379 0.3379 0.4375
06/19/02 0.04 0 0 0.1328 0.3286 0.3286 0.4614
06/20/02 0.06 0 0 0.1992 0.3565 0.3565 0.5557
06/21/02 0.03 0 0 0.0996 0.32705 0.32705 0.42665
06/22/02 0.02 0 0 0.0664 0.2976 0.2976 0.364
06/23/02 0.02 0 0 0.0664 0.2728 0.2728 0.3392
06/24/02 0.03 0 0 0.0996 0.3255 0.3255 0.4251
06/25/02 0 0 0 0.30845 0.30845 0.30845
06/26/02 0.04 0 0 0.1328 0.372 0.372 0.5048
06/27/02 1.7 0.01 0.0159 5.644 0.37665 0.39255 6.02065
06/28/02 6.3 0.02 0.0318 20.916 0 0.0318 20.916
06/29/02 0.4 0.02 0.0318 1.328 0 0.0318 1.328
06/30/02 0.13 0.02 0.0318 0.4316 0 0.0318 0.4316
07/01/02 0.11 0.01 0.0159 0.3652 0.31465 0.33055 0.67985
07/02/02 0.09 0.01 0.0159 0.2988 0.32085 0.33675 0.61965
07/03/02 0.05 0 0 0.166 0.35185 0.35185 0.51785
07/04/02 0.04 0 0 0.1328 0.31775 0.31775 0.45055
07/05/02 0.04 0 0 0.1328 0.3131 0.3131 0.4459
07/06/02 0.03 0 0 0.0996 0.30225 0.30225 0.40185
07/07/02 0.04 0 0 0.1328 0.2821 0.2821 0.4149
07/08/02 0.03 0 0 0.0996 0.32395 0.32395 0.42355
07/09/02 0.03 0 0 0.0996 0.3224 0.3224 0.422
07/10/02 0.03 0 0 0.0996 0.36115 0.36115 0.46075
Roberson (Robeson) Creek TMDL

07/11/02 0.05 0 0 0.166 0.4092 0.4092 0.5752
07/12/02 0.03 0 0 0.0996 0.34875 0.34875 0.44835
07/13/02 0.04 0 0 0.1328 0.30535 0.30535 0.43815
07/14/02 0.03 0 0 0.0996 0.31775 0.31775 0.41735
07/15/02 0.02 0 0 0.0664 0.33635 0.33635 0.40275
07/16/02 0.01 0 0 0.0332 0.31465 0.31465 0.34785
07/17/02 0 0 0 0 0.31775 0.31775 0.31775
07/18/02 0 0 0 0 0.3069 0.3069 0.3069
07/19/02 0 0 0 0 0.3069 0.3069 0.3069
07/20/02 0 0 0 0 0.31155 0.31155 0.31155
07/21/02 0 0 0 0 0.2759 0.2759 0.2759
07/22/02 0 0 0 0 0.3999 0.3999 0.3999
07/23/02 0 0 0 0 0.403 0.403 0.403
07/24/02 1.3 0.23 0.3657 4.316 0.33015 0.69585 4.64615
07/25/02 0.72 0.07 0.1113 2.3904 0.3348 0.4461 2.7252
07/26/02 0.13 0.04 0.0636 0.4316 0.4185 0.4821 0.8501
07/27/02 0.08 0.02 0.0318 0.2656 0.49135 0.52315 0.75695
07/28/02 0.05 0.02 0.0318 0.166 0.33945 0.37125 0.50545
07/29/02 0.03 0.01 0.0159 0.0996 0.33325 0.34915 0.43285
07/30/02 0 0 0 0 0.33015 0.33015 0.33015
07/31/02 0 0 0 0 0.32395 0.32395 0.32395
08/01/02 0 0 0 0 0.3317 0.3317 0.3317
08/02/02 0 0 0 0 0.33325 0.33325 0.33325
08/03/02 0 0 0 0 0.3038 0.3038 0.3038
08/04/02 0 0 0 0 0.28675 0.28675 0.28675
08/05/02 0 0 0 0 0.2976 0.2976 0.2976
08/06/02 0 0 0 0 0.3286 0.3286 0.3286
08/07/02 0 0 0 0 0.3224 0.3224 0.3224
08/08/02 0 0 0 0 0.3472 0.3472 0.3472
08/09/02 0 0 0 0 0.3689 0.3689 0.3689
08/10/02 0 0 0 0 0.27745 0.27745 0.27745
08/11/02 0 0 0 0 0.27125 0.27125 0.27125
Roberson (Robeson) Creek TMDL

08/12/02 0 0 0 0.3379 0.3379 0.3379
08/13/02 0 0 0 0 0.3193 0.3193 0.3193
08/14/02 0.01 0 0 0.0332 0.3348 0.3348 0.368
08/15/02 0.03 0 0 0.0996 0.3906 0.3906 0.4902
08/16/02 0.09 0 0 0.2988 0.35805 0.35805 0.65685
08/17/02 0.22 0 0 0.7304 0.3348 0.3348 1.0652
08/18/02 0.14 0 0 0.4648 0.2976 0.2976 0.7624
08/19/02 0.28 0 0 0.9296 0.3534 0.3534 1.283
08/20/02 0.45 0 0 1.494 0.341 0.341 1.835
08/21/02 0.26 0 0 0.8632 0.33635 0.33635 1.19955
08/22/02 0 0 0 0.3317 0.3317 0.3317
08/23/02 0.07 0 0 0.2324 0.3348 0.3348 0.5672
08/24/02 0.03 0 0 0.0996 0.3379 0.3379 0.4375
08/25/02 0.37 0 0 1.2284 0.2821 0.2821 1.5105
08/26/02 0.61 0 0 2.0252 0.36115 0.36115 2.38635
08/27/02 1.6 0 0 5.312 0.3968 0.3968 5.7088
08/28/02 2.7 0 0 8.964 0.37665 0.37665 9.34065
08/29/02 1.7 0 0 5.644 0.372 0.372 6.016
08/30/02 3.5 0 0 11.62 0.589 0.589 12.209
08/31/02 80 20 31.8 265.6 1.5655 33.3655 267.1655
09/01/02 62 32 50.88 205.84 0.94705 51.82705 206.78705
09/02/02 5.9 2.4 3.816 19.588 0.47895 4.29495 20.06695
09/03/02 3.2 0.83 1.3197 10.624 0.43555 1.75525 11.05955
09/04/02 1.6 0.33 0.5247 5.312 0.4123 0.937 5.7243
09/05/02 0.15 0.2385 0 0.3937 0.6322 0.3937
09/06/02 0.34 0.07 0.1113 1.1288 0.37355 0.48485 1.50235
09/07/02 0.22 0.03 0.0477 0.7304 0.3348 0.3825 1.0652
09/08/02 0.19 0.02 0.0318 0.6308 0.3131 0.3449 0.9439
09/09/02 0.17 0.01 0.0159 0.5644 0.3534 0.3693 0.9178
09/10/02 0.14 0 0 0.4648 0.341 0.341 0.8058
09/11/02 0.13 0 0 0.4316 0.33325 0.33325 0.76485
09/12/02 0.1 0 0 0.332 0.33325 0.33325 0.66525
Roberson (Robeson) Creek TMDL

09/13/02 0.09 0 0 0.2988 0.341 0.341 0.6398
09/14/02 0.1 0 0 0.332 0.5022 0.5022 0.8342
09/15/02 0.69 0 0 2.2908 0.7874 0.7874 3.0782
09/16/02 0.76 0.02 0.0318 2.5232 0.99045 1.02225 3.51365
09/17/02 0.34 0.03 0.0477 1.1288 0.52855 0.57625 1.65735
09/18/02 0.6 0.03 0.0477 1.992 0.4805 0.5282 2.4725
09/19/02 1.2 0.06 0.0954 3.984 0.4619 0.5573 4.4459
09/20/02 0.41 0.09 0.1431 1.3612 0.4712 0.6143 1.8324
09/21/02 0.26 0.05 0.0795 0.8632 0.38905 0.46855 1.25225
09/22/02 0.18 0.03 0.0477 0.5976 0.3627 0.4104 0.9603
09/23/02 0.17 0.02 0.0318 0.5644 0.4185 0.4503 0.9829
09/24/02 0.14 0.01 0.0159 0.4648 0.40765 0.42355 0.87245
09/25/02 0.12 0 0 0.3984 0.41075 0.41075 0.80915
09/26/02 0.13 0 0 0.4316 0.4309 0.4309 0.8625
09/27/02 0.9 0 0 2.988 0.41385 0.41385 3.40185
09/28/02 0.97 0 0 3.2204 0.37665 0.37665 3.59705
09/29/02 0.29 0 0 0.9628 0.33015 0.33015 1.29295
09/30/02 0.18 0 0 0.5976 0.38285 0.38285 0.98045
10/1/02 0 0 0 0.3875 0.3875 0.3875
10/2/02 0 0 0 0.37355 0.37355 0.37355
10/3/02 0 0 0 0.37975 0.37975 0.37975
10/4/02 0 0 0 0.38905 0.38905 0.38905
10/5/02 0 0 0 0.3472 0.3472 0.3472
10/6/02 0 0 0 0.3348 0.3348 0.3348
10/7/02 0 0 0 0.3906 0.3906 0.3906
10/8/02 0 0 0 0.39525 0.39525 0.39525
10/9/02 0 0 0 0.38905 0.38905 0.38905
10/10/02 0 0 0 0.58125 0.58125 0.58125
10/11/02 512 814.08 0 2.1948 816.2748 2.1948
10/12/02 29 46.11 0 0.9424 47.0524 0.9424
10/13/02 6 9.54 0 0.62775 10.16775 0.62775
10/14/02 3.2 5.088 0 0.56575 5.65375 0.56575
Roberson (Robeson) Creek TMDL

10/15/02 1.9 3.021 0 0.62 3.641 0.62
10/16/02 18 28.62 0 1.21985 29.83985 1.21985
10/17/02 7.8 12.402 0 0.7378 13.1398 0.7378
10/18/02 3.6 5.724 0 0.59675 6.32075 0.59675
10/19/02 2.4 3.816 0 0.52235 4.33835 0.52235
10/20/02 1.8 2.862 0 0.48205 3.34405 0.48205
10/21/02 1.5 2.385 0 0.52545 2.91045 0.52545
10/22/02 4.5 7.155 0 0.6293 7.7843 0.6293
10/23/02 3.5 5.565 0 0.5425 6.1075 0.5425
10/24/02 2.3 3.657 0 0.5332 4.1902 0.5332
10/25/02 1.9 3.021 0 0.5394 3.5604 0.5394
10/26/02 1.6 2.544 0 0.4898 3.0338 0.4898
10/27/02 1.6 2.544 0 0.465 3.009 0.465
10/28/02 1.9 3.021 0 0.64015 3.66115 0.64015
10/29/02 11 17.49 0 0.8463 18.3363 0.8463
10/30/02 14 22.26 0 1.0168 23.2768 1.0168
10/31/02 6.9 10.971 0 0.74555 11.71655 0.74555

Roberson (Robeson) Creek TMDL

Appendix V. FLUX water quality sample input files.

RC 8 inflow, flows in cfs, samples in ug/L
DATE flow ammon tkn nox total p total n inorg n org n
04/18/01 3.65 0.10 0.3 5.8 0.35 6.10 5.90 0.20
05/02/01 3.42 0.10 0.8 7.7 0.38 8.50 7.80 0.70
05/09/01 2.34 0.10 0.7 4.6 0.28 5.30 4.70 0.60
05/30/01 2.88 0.10 1.0 11 0.84 12.00 11.10 0.90
06/21/01 2.34 0.33 0.9 1.7 0.20 2.59 2.03 0.56
07/04/01 187.00 0.03 0.7 0.4 0.09 1.06 0.43 0.63
07/23/01 3.00 0.06 0.6 2.5 0.16 3.05 2.56 0.49
07/12/01 3.00 0.29 0.5 1.3 0.11 1.78 1.59 0.19
07/31/01 3.56 0.13 0.5 2.2 0.22 2.74 2.33 0.41
08/05/01 3.00 0.04 0.6 2.3 0.22 2.87 2.34 0.53
08/07/01 2.88 0.06 0.4 1.9 0.23 2.34 1.96 0.38
08/30/01 106.00 0.02 0.4 0.7 0.12 1.09 0.72 0.37
09/09/01 2.34 0.01 0.3 2.7 0.13 3.04 2.71 0.34
09/15/01 2.88 0.01 0.2 2.6 0.13 2.83 2.61 0.22
09/28/01 4.60 0.22 0.8 2.6 0.44 3.37 2.82 0.55
10/04/01 3.00 0.01 0.3 2.6 0.28 2.93 2.61 0.33
10/19/01 3.41 0.20 1.6 2.3 0.15 3.90 2.50 1.40
10/29/01 3.42 0.09 0.7 3.1 0.18 3.84 3.19 0.65

RC 8 inflow, flows in cfs, samples in ug/L
DATE flow ammon tkn nox total p total n inorg n org n
04/15/02 5.90 0.04 0.4 1.2 0.09 1.62 1.24 0.38
05/01/02 3.83 0.04 0.6 2 0.14 2.56 2.04 0.52
05/02/02 3.83 0.06 0.5 3.2 0.23 3.65 3.26 0.39
05/08/02 3.42 0.04 0.4 1.6 0.17 1.98 1.64 0.34
05/14/02 1.62 0.05 0.3 2.1 0.17 2.36 2.15 0.21
05/29/02 1.62 0.03 0.6 3 0.17 3.58 3.03 0.55
06/26/02 0.32 0.01 0.7 1.2 0.29 1.85 1.21 0.65
07/22/02 0.32 0.02 0.9 2.5 0.34 3.42 2.52 0.90
08/15/02 3.54 0.01 0.7 1.1 0.22 1.80 1.11 0.69

Roberson (Robeson) Creek TMDL

Appendix VI. FLUX output files – 2001.

Total P Load with stratification and flow substitution:

Roberson Creek 2001 VAR=total p METHOD= 3 IJC

STRATIFICATION SCHEME:
---- DATE ---- -- SEASON -- -------- FLOW --------
STR >=MIN < MAX >=MIN < MAX >=MIN < MAX
1 0 0 .00 4.00
2 0 0 4.00 209.89

STR SAMPLES EVENTS FLOWS VOLUME %
1 15 15 159 18.60
2 3 3 55 81.40
EXCLUDED 0 0 0 .00
TOTAL 18 18 214 100.00

Roberson Creek 2001 VAR=total p METHOD= 3 IJC
COMPARISON OF SAMPLED AND TOTAL FLOW DISTRIBUTIONS
STR NQ NC NE VOL% TOTAL FLOW SAMPLED FLOW C/Q SLOPE SIGNIF
1 159 15 15 18.6 1.477 1.249 .124 .547
2 55 3 3 81.4 18.682 25.065 -.616 .073
*** 214 18 18 100.0 5.899 5.218

FLOW STATISTICS
FLOW DURATION = 214.0 DAYS = .586 YEARS
MEAN FLOW RATE = 5.899 HM3/YR
TOTAL FLOW VOLUME = 3.46 HM3
FLOW DATE RANGE = 20010401 TO 20011031
SAMPLE DATE RANGE = 20010418 TO 20011029

METHOD MASS (KG) FLUX (KG/YR) FLUX VARIANCE CONC (PPB) CV
1 AV LOAD 618.1 1054.9 .4175E+05 178.84 .194
2 Q WTD C 534.3 911.9 .2998E+05 154.60 .190
3 IJC 512.8 875.2 .2222E+05 148.38 .170
4 REG-1 604.9 1032.5 .1453E+06 175.04 .369
5 REG-2 489.0 834.7 .1116E+07 141.51 1.265
6 REG-3 613.2 1046.6 .4681E+06 177.43 .654

Roberson Creek 2001 VAR=total p METHOD= 3 IJC
X =S FLOW , Y =CONC

BIVARIATE REGRESSION: Y VS. X
INTERCEPT = 2.3472 SLOPE = -.1070
R-SQUARED = .0675 MEAN SQUARED ERROR = .0591
STD ERROR OF SLOPE = .0994 DEGREES OF FREEDOM = 16
T STATISTIC = -1.0765 PROBABILITY(>|T|) = .2980
Y MEAN = 2.3262 Y STD DEVIATION = .2443
X MEAN = .1966 X STD DEVIATION = .5933
RESIDUALS ANALYSIS:
RUNS TEST Z = -2.4794 PROBABILITY (>|Z|) = .0066
LAG-1 AUTOCORREL. = .3340 PROBABILITY (>|R|) = .0782
Roberson (Robeson) Creek TMDL

EFFECTIVE SAMPLES = 9 SLOPE SIGNIFICANCE = .4764

Total N Load with stratification and flow substitution:

Roberson Creek 2001 Total N VAR=total n METHOD= 3 IJC

STRATIFICATION SCHEME:
---- DATE ---- -- SEASON -- -------- FLOW --------
STR >=MIN < MAX >=MIN < MAX >=MIN < MAX
1 0 0 .00 4.00
2 0 0 4.00 209.89

STR SAMPLES EVENTS FLOWS VOLUME %
1 15 15 159 18.60
2 3 3 55 81.40
EXCLUDED 0 0 0 .00
TOTAL 18 18 214 100.00

Roberson Creek 2001 Total N VAR=total n METHOD= 3 IJC
X =S FLOW , Y =CONC

BIVARIATE REGRESSION: Y VS. X
INTERCEPT = 3.5353 SLOPE = -.1518
R-SQUARED = .1146 MEAN SQUARED ERROR = .0666
STD ERROR OF SLOPE = .1055 DEGREES OF FREEDOM = 16
T STATISTIC = -1.4393 PROBABILITY(>|T|) = .1665
Y MEAN = 3.5055 Y STD DEVIATION = .2660
X MEAN = .1966 X STD DEVIATION = .5933
RESIDUALS ANALYSIS:
RUNS TEST Z = -3.0304 PROBABILITY (>|Z|) = .0012
LAG-1 AUTOCORREL. = .5274 PROBABILITY (>|R|) = .0126
EFFECTIVE SAMPLES = 6 SLOPE SIGNIFICANCE = .4562

Roberson Creek 2001 Total N VAR=total n METHOD= 3 IJC
COMPARISON OF SAMPLED AND TOTAL FLOW DISTRIBUTIONS
STR NQ NC NE VOL% TOTAL FLOW SAMPLED FLOW C/Q SLOPE SIGNIF
1 159 15 15 18.6 1.477 1.249 .261 .148
2 55 3 3 81.4 18.682 25.065 -.865 .047
*** 214 18 18 100.0 5.899 5.218

FLOW STATISTICS
FLOW DURATION = 214.0 DAYS = .586 YEARS
MEAN FLOW RATE = 5.899 HM3/YR
TOTAL FLOW VOLUME = 3.46 HM3
FLOW DATE RANGE = 20010401 TO 20011031
SAMPLE DATE RANGE = 20010418 TO 20011029

METHOD MASS (KG) FLUX (KG/YR) FLUX VARIANCE CONC (PPB) CV
1 AV LOAD 7983.0 13625.2 .3759E+07 2309.91 .142
2 Q WTD C 7141.8 12189.5 .6553E+07 2066.51 .210
3 IJC 6738.2 11500.7 .3106E+07 1949.73 .153
4 REG-1 8420.1 14371.2 .8199E+07 2436.38 .199
5 REG-2 7667.3 13086.3 .7740E+07 2218.55 .213
6 REG-3 8707.0 14861.0 .1061E+08 2519.41 .219
Roberson (Robeson) Creek TMDL

Roberson Creek 2001 Total N VAR=total n METHOD= 3 IJC
X =S FLOW , Y =CONC

BIVARIATE REGRESSION: Y VS. X
INTERCEPT = 3.5353 SLOPE = -.1518
R-SQUARED = .1146 MEAN SQUARED ERROR = .0666
STD ERROR OF SLOPE = .1055 DEGREES OF FREEDOM = 16
T STATISTIC = -1.4393 PROBABILITY(>|T|) = .1665
Y MEAN = 3.5055 Y STD DEVIATION = .2660
X MEAN = .1966 X STD DEVIATION = .5933
RESIDUALS ANALYSIS:
RUNS TEST Z = -3.0304 PROBABILITY (>|Z|) = .0012
LAG-1 AUTOCORREL. = .5274 PROBABILITY (>|R|) = .0126
EFFECTIVE SAMPLES = 6 SLOPE SIGNIFICANCE = .4562

Roberson Creek 2001 Total N VAR=total n METHOD= 3 IJC
X =S FLOW , Y =RESIDUAL

BIVARIATE REGRESSION: Y VS. X
INTERCEPT = -.1322 SLOPE = .1743
R-SQUARED = .1372 MEAN SQUARED ERROR = .0715
STD ERROR OF SLOPE = .1093 DEGREES OF FREEDOM = 16
T STATISTIC = 1.5950 PROBABILITY(>|T|) = .1271
Y MEAN = -.0979 Y STD DEVIATION = .2792
X MEAN = .1966 X STD DEVIATION = .5933
RESIDUALS ANALYSIS:
RUNS TEST Z = -3.0304 PROBABILITY (>|Z|) = .0012
LAG-1 AUTOCORREL. = .3787 PROBABILITY (>|R|) = .0540
EFFECTIVE SAMPLES = 8 SLOPE SIGNIFICANCE = .3297

Roberson Creek 2001 Total N VAR=total n METHOD= 3 IJC
X =DATE , Y =RESIDUAL

BIVARIATE REGRESSION: Y VS. X
INTERCEPT = 2046.2870 SLOPE = -1.0224
R-SQUARED = .3511 MEAN SQUARED ERROR = .0537
STD ERROR OF SLOPE = .3475 DEGREES OF FREEDOM = 16
T STATISTIC = -2.9422 PROBABILITY(>|T|) = .0093
Y MEAN = -.0979 Y STD DEVIATION = .2792
X MEAN = 2001.5778 X STD DEVIATION = .1618
RESIDUALS ANALYSIS:
RUNS TEST Z = -1.1762 PROBABILITY (>|Z|) = .1197
LAG-1 AUTOCORREL. = .1124 PROBABILITY (>|R|) = .3166
EFFECTIVE SAMPLES = 14 SLOPE SIGNIFICANCE = .0224

Roberson Creek 2001 Total N VAR=total n METHOD= 1 AV LOAD
X =S FLOW , Y =RESIDUAL

BIVARIATE REGRESSION: Y VS. X
INTERCEPT = -.3080 SLOPE = .4521
R-SQUARED = .4054 MEAN SQUARED ERROR = .1122
STD ERROR OF SLOPE = .1369 DEGREES OF FREEDOM = 16
T STATISTIC = 3.3025 PROBABILITY(>|T|) = .0047
Y MEAN = -.2191 Y STD DEVIATION = .4214
Roberson (Robeson) Creek TMDL

X MEAN = .1966 X STD DEVIATION = .5933
RESIDUALS ANALYSIS:
RUNS TEST Z = -.5413 PROBABILITY (>|Z|) = .2941
LAG-1 AUTOCORREL. = .3605 PROBABILITY (>|R|) = .0631
EFFECTIVE SAMPLES = 8 SLOPE SIGNIFICANCE = .0685

Roberson Creek 2001 Total N VAR=total n METHOD= 1 AV LOAD
X =DATE , Y =RESIDUAL

BIVARIATE REGRESSION: Y VS. X
INTERCEPT = 3381.4190 SLOPE = -1.6895
R-SQUARED = .4209 MEAN SQUARED ERROR = .1093
STD ERROR OF SLOPE = .4955 DEGREES OF FREEDOM = 16
T STATISTIC = -3.4099 PROBABILITY(>|T|) = .0038
Y MEAN = -.2191 Y STD DEVIATION = .4214
X MEAN = 2001.5778 X STD DEVIATION = .1618
RESIDUALS ANALYSIS:
RUNS TEST Z = -.1915 PROBABILITY (>|Z|) = .4240
LAG-1 AUTOCORREL. = -.0079 PROBABILITY (>|R|) = .4867
EFFECTIVE SAMPLES = 18 SLOPE SIGNIFICANCE = .0038

Roberson Creek 2001 Total N VAR=total n METHOD= 1 AV LOAD
X =S FLOW , Y =CONC

BIVARIATE REGRESSION: Y VS. X
INTERCEPT = 3.5353 SLOPE = -.1518
R-SQUARED = .1146 MEAN SQUARED ERROR = .0666
STD ERROR OF SLOPE = .1055 DEGREES OF FREEDOM = 16
T STATISTIC = -1.4393 PROBABILITY(>|T|) = .1665
Y MEAN = 3.5055 Y STD DEVIATION = .2660
X MEAN = .1966 X STD DEVIATION = .5933
RESIDUALS ANALYSIS:
RUNS TEST Z = -3.0304 PROBABILITY (>|Z|) = .0012
LAG-1 AUTOCORREL. = .5274 PROBABILITY (>|R|) = .0126
EFFECTIVE SAMPLES = 6 SLOPE SIGNIFICANCE = .4562

Inorganic N Load with stratification and with flow substitution:

Roberson Creek 2001 VAR=inorg n METHOD= 3 IJC

STRATIFICATION SCHEME:
---- DATE ---- -- SEASON -- -------- FLOW --------
STR >=MIN < MAX >=MIN < MAX >=MIN < MAX
1 0 0 .00 4.00
2 0 0 4.00 209.89

STR SAMPLES EVENTS FLOWS VOLUME %
1 15 15 159 18.60
2 3 3 55 81.40
EXCLUDED 0 0 0 .00
TOTAL 18 18 214 100.00

Roberson (Robeson) Creek TMDL

Roberson Creek 2001 VAR=inorg n METHOD= 3 IJC
COMPARISON OF SAMPLED AND TOTAL FLOW DISTRIBUTIONS
STR NQ NC NE VOL% TOTAL FLOW SAMPLED FLOW C/Q SLOPE SIGNIF
1 159 15 15 18.6 1.477 1.249 .275 .149
2 55 3 3 81.4 18.682 25.065 -1.195 .062
*** 214 18 18 100.0 5.899 5.218

FLOW STATISTICS
FLOW DURATION = 214.0 DAYS = .586 YEARS
MEAN FLOW RATE = 5.899 HM3/YR
TOTAL FLOW VOLUME = 3.46 HM3
FLOW DATE RANGE = 20010401 TO 20011031
SAMPLE DATE RANGE = 20010418 TO 20011029

METHOD MASS (KG) FLUX (KG/YR) FLUX VARIANCE CONC (PPB) CV
1 AV LOAD 5805.5 9908.8 .3282E+07 1679.85 .183
2 Q WTD C 5381.2 9184.6 .7814E+07 1557.08 .304
3 IJC 4929.7 8414.0 .3629E+07 1426.44 .226
4 REG-1 6579.9 11230.4 .2452E+08 1903.91 .441
5 REG-2 7408.4 12644.4 .2191E+10 2143.63 3.702
6 REG-3 6916.4 11804.7 .9750E+09 2001.27 2.645

Roberson Creek 2001 VAR=inorg n METHOD= 1 AV LOAD
X =S FLOW , Y =RESIDUAL

BIVARIATE REGRESSION: Y VS. X
INTERCEPT = -.4624 SLOPE = .7581
R-SQUARED = .6998 MEAN SQUARED ERROR = .0922
STD ERROR OF SLOPE = .1241 DEGREES OF FREEDOM = 16
T STATISTIC = 6.1072 PROBABILITY(>|T|) = .0001
Y MEAN = -.3133 Y STD DEVIATION = .5377
X MEAN = .1966 X STD DEVIATION = .5933
RESIDUALS ANALYSIS:
RUNS TEST Z = -3.4156 PROBABILITY (>|Z|) = .0003
LAG-1 AUTOCORREL. = .5228 PROBABILITY (>|R|) = .0133
EFFECTIVE SAMPLES = 6 SLOPE SIGNIFICANCE = .0251

Roberson Creek 2001 VAR=inorg n METHOD= 1 AV LOAD
X =DATE , Y =RESIDUAL

BIVARIATE REGRESSION: Y VS. X
INTERCEPT = 4464.9610 SLOPE = -2.2309
R-SQUARED = .4506 MEAN SQUARED ERROR = .1688
STD ERROR OF SLOPE = .6158 DEGREES OF FREEDOM = 16
T STATISTIC = -3.6229 PROBABILITY(>|T|) = .0026
Y MEAN = -.3133 Y STD DEVIATION = .5377
X MEAN = 2001.5778 X STD DEVIATION = .1618
RESIDUALS ANALYSIS:
RUNS TEST Z = -.1915 PROBABILITY (>|Z|) = .4240
LAG-1 AUTOCORREL. = -.0546 PROBABILITY (>|R|) = .4084
EFFECTIVE SAMPLES = 18 SLOPE SIGNIFICANCE = .0026

Roberson Creek 2001 VAR=inorg n METHOD= 3 IJC
X =S FLOW , Y =RESIDUAL

Roberson (Robeson) Creek TMDL

BIVARIATE REGRESSION: Y VS. X
INTERCEPT = .3236 SLOPE = -.2419
R-SQUARED = .1918 MEAN SQUARED ERROR = .0922
STD ERROR OF SLOPE = .1241 DEGREES OF FREEDOM = 16
T STATISTIC = -1.9489 PROBABILITY(>|T|) = .0663
Y MEAN = .2760 Y STD DEVIATION = .3277
X MEAN = .1966 X STD DEVIATION = .5933
RESIDUALS ANALYSIS:
RUNS TEST Z = -3.4156 PROBABILITY (>|Z|) = .0003
LAG-1 AUTOCORREL. = .5228 PROBABILITY (>|R|) = .0133
EFFECTIVE SAMPLES = 6 SLOPE SIGNIFICANCE = .3243

Roberson Creek 2001 VAR=inorg n METHOD= 3 IJC
X =DATE , Y =RESIDUAL

BIVARIATE REGRESSION: Y VS. X
INTERCEPT = 1468.6420 SLOPE = -.7336
R-SQUARED = .1312 MEAN SQUARED ERROR = .0991
STD ERROR OF SLOPE = .4720 DEGREES OF FREEDOM = 16
T STATISTIC = -1.5543 PROBABILITY(>|T|) = .1366
Y MEAN = .2760 Y STD DEVIATION = .3277
X MEAN = 2001.5778 X STD DEVIATION = .1618
RESIDUALS ANALYSIS:
RUNS TEST Z = -3.1457 PROBABILITY (>|Z|) = .0008
LAG-1 AUTOCORREL. = .3192 PROBABILITY (>|R|) = .0878
EFFECTIVE SAMPLES = 9 SLOPE SIGNIFICANCE = .3088

Roberson (Robeson) Creek TMDL

Appendix VII . FLUX output files – 2002

Roberson Creek 2002 Total P VAR=total p METHOD= 1 AV LOAD
Comparison of Sampled & Total Flow Distributions
------ SAMPLED ----- ------- TOTAL ------
STRAT N MEAN STD DEV N MEAN STD DEV DIFF T PROB(>T)
1 9 2.42 1.66 214 6.21 50.50 -3.79 1.08 .280
*** 9 2.42 1.66 214 6.21 50.50 -3.79 1.08 .280

Average Sample Interval = 13.6 Days, Date Range = 20020415 to 20020815
Maximum Sample Interval = 27 Days, Date Range = 20020529 to 20020626
Percent of Total Flow Volume Occuring In This Interval = .7%

Total Flow Volume on Sampled Days = 11.1 hm3
Total Flow Volume on All Days = 1328.9 hm3
Percent of Total Flow Volume Sampled = .8%

Maximum Sampled Flow Rate = 5.27 hm3/yr
Maximum Total Flow Rate = 729.50 hm3/yr
Number of Days when Flow Exceeded Maximum Sampled Flow = 26 out of 214
Percent of Total Flow Volume Occurring at Flow Rates Exceeding the
Maximum Sampled Flow Rate = 88.5%

Roberson Creek 2002 Total P VAR=total p METHOD= 1 AV LOAD
Comparison of Sampled & Total Flow Distributions
------ SAMPLED ----- ------- TOTAL ------
STRAT N MEAN STD DEV N MEAN STD DEV DIFF T PROB(>T)
1 9 1.23 1.34 214 6.21 50.50 -4.98 1.43 .150
*** 9 1.23 1.34 214 6.21 50.50 -4.98 1.43 .150

Average Sample Interval = 13.6 Days, Date Range = 20020415 to 20020815
Maximum Sample Interval = 27 Days, Date Range = 20020529 to 20020626
Percent of Total Flow Volume Occuring In This Interval = .7%

Total Flow Volume on Sampled Days = 11.1 hm3
Total Flow Volume on All Days = 1328.9 hm3
Percent of Total Flow Volume Sampled = .8%

Maximum Sampled Flow Rate = 4.46 hm3/yr
Maximum Total Flow Rate = 729.50 hm3/yr
Number of Days when Flow Exceeded Maximum Sampled Flow = 28 out of 214
Percent of Total Flow Volume Occurring at Flow Rates Exceeding the
Maximum Sampled Flow Rate = 89.3%

Roberson Creek 2002 Total P VAR=total p METHOD= 1 AV LOAD
COMPARISON OF SAMPLED AND TOTAL FLOW DISTRIBUTIONS
STR NQ NC NE VOL% TOTAL FLOW SAMPLED FLOW C/Q SLOPE SIGNIF
1 214 9 9 100.0 6.210 2.423 -.283 .015
*** 214 9 9 100.0 6.210 2.423

FLOW STATISTICS
FLOW DURATION = 214.0 DAYS = .586 YEARS
MEAN FLOW RATE = 6.210 HM3/YR
TOTAL FLOW VOLUME = 3.64 HM3
Roberson (Robeson) Creek TMDL

10
FLOW DATE RANGE = 20020401 TO 20021031
SAMPLE DATE RANGE = 20020415 TO 20020815

METHOD MASS (KG) FLUX (KG/YR) FLUX VARIANCE CONC (PPB) CV
1 AV LOAD 236.3 403.2 .6989E+04 64.94 .207
2 Q WTD C 605.5 1033.4 .2908E+05 166.42 .165
3 IJC 596.6 1018.3 .3363E+05 163.99 .180
4 REG-1 486.0 829.5 .3077E+05 133.58 .211
6 REG-3 546.7 933.0 .2169E+05 150.25 .158

Roberson Creek 2002 Total P VAR=total p METHOD= 2 Q WTD C
X =S FLOW , Y =RESIDUAL

BIVARIATE REGRESSION: Y VS. X
INTERCEPT = .1186 SLOPE = -.2827
R-SQUARED = .5941 MEAN SQUARED ERROR = .0138
STD ERROR OF SLOPE = .0883 DEGREES OF FREEDOM = 7
T STATISTIC = -3.2009 PROBABILITY(>|T|) = .0148
Y MEAN = .0554 Y STD DEVIATION = .1726
X MEAN = .2234 X STD DEVIATION = .4706
RESIDUALS ANALYSIS:
RUNS TEST Z = -1.4056 PROBABILITY (>|Z|) = .0799
LAG-1 AUTOCORREL. = .1422 PROBABILITY (>|R|) = .3348
EFFECTIVE SAMPLES = 6 SLOPE SIGNIFICANCE = .0592

Roberson Creek 2002 Total P VAR=total p METHOD= 2 Q WTD C
X =DATE , Y =RESIDUAL

BIVARIATE REGRESSION: Y VS. X
INTERCEPT = -2182.1680 SLOPE = 1.0898
R-SQUARED = .5174 MEAN SQUARED ERROR = .0164
STD ERROR OF SLOPE = .3978 DEGREES OF FREEDOM = 7
T STATISTIC = 2.7392 PROBABILITY(>|T|) = .0281
Y MEAN = .0554 Y STD DEVIATION = .1726
X MEAN = 2002.4145 X STD DEVIATION = .1139
RESIDUALS ANALYSIS:
RUNS TEST Z = -.6827 PROBABILITY (>|Z|) = .2474
LAG-1 AUTOCORREL. = -.0397 PROBABILITY (>|R|) = .4526
EFFECTIVE SAMPLES = 9 SLOPE SIGNIFICANCE = .0281

Roberson Creek 2002 Total P VAR=total p METHOD= 3 IJC
X =S FLOW , Y =RESIDUAL

BIVARIATE REGRESSION: Y VS. X
INTERCEPT = .1250 SLOPE = -.2827
R-SQUARED = .5941 MEAN SQUARED ERROR = .0138
STD ERROR OF SLOPE = .0883 DEGREES OF FREEDOM = 7
T STATISTIC = -3.2009 PROBABILITY(>|T|) = .0148
Y MEAN = .0618 Y STD DEVIATION = .1726
X MEAN = .2234 X STD DEVIATION = .4706
RESIDUALS ANALYSIS:
RUNS TEST Z = -1.4056 PROBABILITY (>|Z|) = .0799
LAG-1 AUTOCORREL. = .1422 PROBABILITY (>|R|) = .3348
EFFECTIVE SAMPLES = 6 SLOPE SIGNIFICANCE = .0592

Roberson Creek 2002 Total P VAR=total p METHOD= 3 IJC
Roberson (Robeson) Creek TMDL

X =DATE , Y =RESIDUAL

BIVARIATE REGRESSION: Y VS. X
INTERCEPT = -2182.1620 SLOPE = 1.0898
R-SQUARED = .5174 MEAN SQUARED ERROR = .0164
STD ERROR OF SLOPE = .3978 DEGREES OF FREEDOM = 7
T STATISTIC = 2.7392 PROBABILITY(>|T|) = .0281
Y MEAN = .0618 Y STD DEVIATION = .1726
X MEAN = 2002.4145 X STD DEVIATION = .1139
RESIDUALS ANALYSIS:
RUNS TEST Z = -.6827 PROBABILITY (>|Z|) = .2474
LAG-1 AUTOCORREL. = -.0396 PROBABILITY (>|R|) = .4527
EFFECTIVE SAMPLES = 9 SLOPE SIGNIFICANCE = .0281

Roberson Creek 2002 Total N VAR=total n METHOD= 3 IJC
COMPARISON OF SAMPLED AND TOTAL FLOW DISTRIBUTIONS
STR NQ NC NE VOL% TOTAL FLOW SAMPLED FLOW C/Q SLOPE SIGNIF
1 214 9 9 100.0 6.210 2.423 -.067 .562
*** 214 9 9 100.0 6.210 2.423

FLOW STATISTICS
FLOW DURATION = 214.0 DAYS = .586 YEARS
MEAN FLOW RATE = 6.210 HM3/YR
TOTAL FLOW VOLUME = 3.64 HM3
FLOW DATE RANGE = 20020401 TO 20021031
SAMPLE DATE RANGE = 20020415 TO 20020815

METHOD MASS (KG) FLUX (KG/YR) FLUX VARIANCE CONC (PPB) CV
1 AV LOAD 3362.5 5739.1 .1642E+07 924.21 .223
2 Q WTD C 8617.8 14708.6 .4664E+07 2368.65 .147
3 IJC 8533.4 14564.5 .5051E+07 2345.45 .154
4 REG-1 8183.1 13966.7 .9254E+07 2249.17 .218
6 REG-3 8721.9 14886.4 .6654E+07 2397.29 .173

Roberson Creek 2002 Total N VAR=total n METHOD= 2 Q WTD C
X =S FLOW , Y =RESIDUAL

BIVARIATE REGRESSION: Y VS. X
INTERCEPT = .0248 SLOPE = -.0666
R-SQUARED = .0516 MEAN SQUARED ERROR = .0206
STD ERROR OF SLOPE = .1079 DEGREES OF FREEDOM = 7
T STATISTIC = -.6171 PROBABILITY(>|T|) = .5616
Y MEAN = .0099 Y STD DEVIATION = .1379
X MEAN = .2234 X STD DEVIATION = .4706
RESIDUALS ANALYSIS:
RUNS TEST Z = .7631 PROBABILITY (>|Z|) = .2227
LAG-1 AUTOCORREL. = -.4729 PROBABILITY (>|R|) = .0780
EFFECTIVE SAMPLES = 9 SLOPE SIGNIFICANCE = .5616

Roberson Creek 2002 Total N VAR=total n METHOD= 2 Q WTD C
X =DATE , Y =RESIDUAL

BIVARIATE REGRESSION: Y VS. X
INTERCEPT = 54.6564 SLOPE = -.0273
R-SQUARED = .0005 MEAN SQUARED ERROR = .0217
Roberson (Robeson) Creek TMDL

STD ERROR OF SLOPE = .4574 DEGREES OF FREEDOM = 7
T STATISTIC = -.0597 PROBABILITY(>|T|) = .9529
Y MEAN = .0099 Y STD DEVIATION = .1379
X MEAN = 2002.4145 X STD DEVIATION = .1139
RESIDUALS ANALYSIS:
RUNS TEST Z = .7631 PROBABILITY (>|Z|) = .2227
LAG-1 AUTOCORREL. = -.4800 PROBABILITY (>|R|) = .0749
EFFECTIVE SAMPLES = 9 SLOPE SIGNIFICANCE = .9529

Roberson Creek 2002 Inorganic N VAR=inorg n METHOD= 2 Q WTD C
COMPARISON OF SAMPLED AND TOTAL FLOW DISTRIBUTIONS
STR NQ NC NE VOL% TOTAL FLOW SAMPLED FLOW C/Q SLOPE SIGNIF
1 214 9 9 100.0 6.210 2.423 -.028 .841
*** 214 9 9 100.0 6.210 2.423

FLOW STATISTICS
FLOW DURATION = 214.0 DAYS = .586 YEARS
MEAN FLOW RATE = 6.210 HM3/YR
TOTAL FLOW VOLUME = 3.64 HM3
FLOW DATE RANGE = 20020401 TO 20021031
SAMPLE DATE RANGE = 20020415 TO 20020815

METHOD MASS (KG) FLUX (KG/YR) FLUX VARIANCE CONC (PPB) CV
1 AV LOAD 2719.1 4641.0 .1239E+07 747.38 .240
2 Q WTD C 6968.9 11894.3 .4694E+07 1915.44 .182
3 IJC 6892.1 11763.3 .4990E+07 1894.35 .190
4 REG-1 6818.5 11637.7 .1032E+08 1874.12 .276
6 REG-3 7310.4 12477.1 .7851E+07 2009.30 .225

Roberson Creek 2002 Inorganic N VAR=inorg n METHOD= 2 Q WTD C
X =S FLOW , Y =RESIDUAL

BIVARIATE REGRESSION: Y VS. X
INTERCEPT = -.0013 SLOPE = -.0280
R-SQUARED = .0056 MEAN SQUARED ERROR = .0351
STD ERROR OF SLOPE = .1407 DEGREES OF FREEDOM = 7
T STATISTIC = -.1994 PROBABILITY(>|T|) = .8412
Y MEAN = -.0075 Y STD DEVIATION = .1756
X MEAN = .2234 X STD DEVIATION = .4706
RESIDUALS ANALYSIS:
RUNS TEST Z = .7631 PROBABILITY (>|Z|) = .2227
LAG-1 AUTOCORREL. = -.3710 PROBABILITY (>|R|) = .1329
EFFECTIVE SAMPLES = 9 SLOPE SIGNIFICANCE = .8412

Roberson Creek 2002 Inorganic N VAR=inorg n METHOD= 2 Q WTD C
X =DATE , Y =RESIDUAL

BIVARIATE REGRESSION: Y VS. X
INTERCEPT = 820.1454 SLOPE = -.4096
R-SQUARED = .0706 MEAN SQUARED ERROR = .0328
STD ERROR OF SLOPE = .5618 DEGREES OF FREEDOM = 7
T STATISTIC = -.7291 PROBABILITY(>|T|) = .4947
Y MEAN = -.0075 Y STD DEVIATION = .1756
X MEAN = 2002.4145 X STD DEVIATION = .1139
RESIDUALS ANALYSIS:
RUNS TEST Z = .7631 PROBABILITY (>|Z|) = .2227
Roberson (Robeson) Creek TMDL

LAG-1 AUTOCORREL. = -.4542 PROBABILITY (>|R|) = .0865
EFFECTIVE SAMPLES = 9 SLOPE SIGNIFICANCE = .4947

Roberson Creek 2002 Inorganic N VAR=inorg n METHOD= 2 Q WTD C
X =S FLOW , Y =CONC

BIVARIATE REGRESSION: Y VS. X
INTERCEPT = 3.2810 SLOPE = -.0280
R-SQUARED = .0056 MEAN SQUARED ERROR = .0351
STD ERROR OF SLOPE = .1407 DEGREES OF FREEDOM = 7
T STATISTIC = -.1994 PROBABILITY(>|T|) = .8412
Y MEAN = 3.2747 Y STD DEVIATION = .1756
X MEAN = .2234 X STD DEVIATION = .4706
RESIDUALS ANALYSIS:
RUNS TEST Z = .7631 PROBABILITY (>|Z|) = .2227
LAG-1 AUTOCORREL. = -.3710 PROBABILITY (>|R|) = .1329
EFFECTIVE SAMPLES = 9 SLOPE SIGNIFICANCE = .8412

Verification Loads: Apr-Sep 2002

Roberson Verification VAR=total p METHOD= 2 Q WTD C
Comparison of Sampled & Total Flow Distributions
------ SAMPLED ----- ------- TOTAL ------
STRAT N MEAN STD DEV N MEAN STD DEV DIFF T PROB(>T)
1 9 2.42 1.66 183 2.23 8.99 .20 -.23 .815
*** 9 2.42 1.66 183 2.23 8.99 .20 -.23 .815

Average Sample Interval = 13.6 Days, Date Range = 20020415 to 20020815
Maximum Sample Interval = 27 Days, Date Range = 20020529 to 20020626
Percent of Total Flow Volume Occuring In This Interval = 2.2%

Total Flow Volume on Sampled Days = 11.1 hm3
Total Flow Volume on All Days = 407.2 hm3
Percent of Total Flow Volume Sampled = 2.7%

Maximum Sampled Flow Rate = 5.27 hm3/yr
Maximum Total Flow Rate = 104.62 hm3/yr
Number of Days when Flow Exceeded Maximum Sampled Flow = 15 out of 183
Percent of Total Flow Volume Occurring at Flow Rates Exceeding the
Maximum Sampled Flow Rate = 71.6%

Roberson Verification VAR=total p METHOD= 2 Q WTD C
COMPARISON OF SAMPLED AND TOTAL FLOW DISTRIBUTIONS
STR NQ NC NE VOL% TOTAL FLOW SAMPLED FLOW C/Q SLOPE SIGNIF
1 183 9 9 100.0 2.225 2.423 -.283 .015
*** 183 9 9 100.0 2.225 2.423

FLOW STATISTICS
FLOW DURATION = 183.0 DAYS = .501 YEARS
MEAN FLOW RATE = 2.225 HM3/YR
TOTAL FLOW VOLUME = 1.11 HM3
FLOW DATE RANGE = 20020401 TO 20020930
SAMPLE DATE RANGE = 20020415 TO 20020815

METHOD MASS (KG) FLUX (KG/YR) FLUX VARIANCE CONC (PPB) CV
Roberson (Robeson) Creek TMDL

1 AV LOAD 202.0 403.2 .6989E+04 181.23 .207
2 Q WTD C 185.5 370.3 .3733E+04 166.42 .165
3 IJC 182.8 364.9 .4318E+04 163.99 .180
4 REG-1 190.0 379.3 .2914E+04 170.48 .142
6 REG-3 185.6 370.5 .2136E+04 166.51 .125

Roberson Verification VAR=total p METHOD= 2 Q WTD C
X =S FLOW , Y =RESIDUAL

BIVARIATE REGRESSION: Y VS. X
INTERCEPT = .1186 SLOPE = -.2827
R-SQUARED = .5941 MEAN SQUARED ERROR = .0138
STD ERROR OF SLOPE = .0883 DEGREES OF FREEDOM = 7
T STATISTIC = -3.2009 PROBABILITY(>|T|) = .0148
Y MEAN = .0554 Y STD DEVIATION = .1726
X MEAN = .2234 X STD DEVIATION = .4706
RESIDUALS ANALYSIS:
RUNS TEST Z = -1.4056 PROBABILITY (>|Z|) = .0799
LAG-1 AUTOCORREL. = .1422 PROBABILITY (>|R|) = .3348
EFFECTIVE SAMPLES = 6 SLOPE SIGNIFICANCE = .0592

Roberson Verification VAR=total p METHOD= 2 Q WTD C
X =DATE , Y =RESIDUAL

BIVARIATE REGRESSION: Y VS. X
INTERCEPT = -2182.1680 SLOPE = 1.0898
R-SQUARED = .5174 MEAN SQUARED ERROR = .0164
STD ERROR OF SLOPE = .3978 DEGREES OF FREEDOM = 7
T STATISTIC = 2.7392 PROBABILITY(>|T|) = .0281
Y MEAN = .0554 Y STD DEVIATION = .1726
X MEAN = 2002.4145 X STD DEVIATION = .1139
RESIDUALS ANALYSIS:
RUNS TEST Z = -.6827 PROBABILITY (>|Z|) = .2474
LAG-1 AUTOCORREL. = -.0397 PROBABILITY (>|R|) = .4526
EFFECTIVE SAMPLES = 9 SLOPE SIGNIFICANCE = .0281

Roberson (Robeson) Creek TMDL

Appendix VIII. BATHTUB calibration input files and output.

Uncalibrated Model:

Roberson Creek Cove 2001

MODEL OPTIONS:
1 CONSERVATIVE SUBSTANCE 0 NOT COMPUTED
2 PHOSPHORUS BALANCE 2 2ND ORDER, DECAY
3 NITROGEN BALANCE 4 BACHMAN VOL. LOAD
4 CHLOROPHYLL-A 3 P, N, LOW-TURBIDITY
5 SECCHI DEPTH 1 VS. CHLA & TURBIDITY
6 DISPERSION 1 FISCHER-NUMERIC
7 PHOSPHORUS CALIBRATION 1 DECAY RATES
8 NITROGEN CALIBRATION 1 DECAY RATES
9 ERROR ANALYSIS 1 MODEL & DATA
10 AVAILABILITY FACTORS 1 USE FOR MODEL 1 ONLY
11 MASS-BALANCE TABLES 1 USE ESTIMATED CONCS

ATMOSPHERIC LOADS & AVAILABILITY FACTORS:
ATMOSPHERIC-LOADS AVAILABILITY
VARIABLE KG/KM2-YR CV FACTOR
1 CONSERV .00 .00 .00
2 TOTAL P 65.00 .50 1.33
3 TOTAL N 536.00 .50 .59
4 ORTHO P 32.50 .50 .33
5 INORG N 359.00 .50 .79

GLOBAL INPUT VALUES:
PARAMETER MEAN CV
PERIOD LENGTH YRS .586 .000
PRECIPITATION M .532 .200
EVAPORATION M .690 .300
INCREASE IN STORAGE M .000 .000

TRIBUTARY DRAINAGE AREAS AND FLOWS:
ID TYPE SEG NAME DRAINAGE AREA MEAN FLOW CV OF MEAN FLOW
KM2 HM3/YR
1 1 1 Roberson RC8 74.240 6.860 .201

TRIBUTARY CONCENTRATIONS (PPB): MEAN/CV
ID CONSERV TOTAL P TOTAL N ORTHO P INORG N
1 .0/ .00 148.4/ .17 1949.7/ .15 103.9/ .17 1426.4/ .23

MODEL SEGMENTS & CALIBRATION FACTORS:
----------- CALIBRATION FACTORS -----------
SEG OUTFLOW GROUP SEGMENT NAME P SED N SED CHL-A SECCHI HOD DISP
1 0 1 Roberson 1.00 1.00 1.00 1.00 1.00 1.000
CV: .000 .000 .000 .000 .000 .000

SEGMENT MORPHOMETRY: MEAN/CV
LENGTH AREA ZMEAN ZMIX ZHYP
ID LABEL KM KM2 M M M
1 Roberson 1.75 .1300 4.50 4.24/ .00 .00/ .00

Roberson (Robeson) Creek TMDL

SEGMENT OBSERVED WATER QUALITY:
SEG TURBID CONSER TOTALP TOTALN CHL-A SECCHI ORG-N TP-OP HODV MODV
1/M --- MG/M3 MG/M3 MG/M3 M MG/M3 MG/M3 MG/M3-D MG/M3-D
1 MN: .00 .0 93.8 1308.1 32.9 .4 876.2 .0 .0 .0
CV: .00 .00 .06 .08 .17 .13 .10 .00 .00 .00

MODEL COEFFICIENTS:
COEFFICIENT MEAN CV
DISPERSION FACTO 1.000 .70
P DECAY RATE 1.000 .45
N DECAY RATE 1.000 .55
CHL-A MODEL 1.000 .26
SECCHI MODEL 1.000 .10
ORGANIC N MODEL 1.000 .12
TP-OP MODEL 1.000 .15
HODV MODEL 1.000 .15
MODV MODEL 1.000 .22
BETA M2/MG .025 .00
MINIMUM QS 4.000 .00
FLUSHING EFFECT 1.000 .00
CHLOROPHYLL-A CV .620 .00

CASE NOTES:
single reservoir

spatially averaged

Water Balance:

CASE: Roberson Creek Cove 2001
HYDRAULIC AND DISPERSION PARAMETERS:
NET RESIDENCE OVERFLOW MEAN ----DISPERSION----- EXCHANGE
INFLOW TIME RATE VELOCITY ESTIMATED NUMERIC RATE
SEG OUT HM3/YR YRS M/YR KM/YR KM2/YR KM2/YR HM3/YR
1 0 6.82 .08571 52.5 20.4 3. 18. 0.
CASE: Roberson Creek Cove 2001
GROSS WATER BALANCE:
DRAINAGE AREA ---- FLOW (HM3/YR) ---- RUNOFF
ID T LOCATION KM2 MEAN VARIANCE CV M/YR
----------------------------------------------------------------------------
1 1 Roberson RC8 74.240 6.860 .190E+01 .201 .092
----------------------------------------------------------------------------
PRECIPITATION .130 .118 .557E-03 .200 .908
TRIBUTARY INFLOW 74.240 6.860 .190E+01 .201 .092
***TOTAL INFLOW 74.370 6.978 .190E+01 .198 .094
ADVECTIVE OUTFLOW 74.370 6.825 .190E+01 .202 .092
***TOTAL OUTFLOW 74.370 6.825 .190E+01 .202 .092
***EVAPORATION .000 .153 .211E-02 .300 .000
----------------------------------------------------------------------------

GROSS MASS BALANCE BASED UPON ESTIMATED CONCENTRATIONS
COMPONENT: TOTAL P
----- LOADING ---- --- VARIANCE --- CONC EXPORT
Roberson (Robeson) Creek TMDL

ID T LOCATION KG/YR %(I) KG/YR**2 %(I) CV MG/M3 KG/KM2
-------------------------------------------------------------------------------
1 1 Roberson RC8 1017.9 99.2 .718E+05 100.0 .263 148.4 13.7
-------------------------------------------------------------------------------
PRECIPITATION 8.4 .8 .179E+02 .0 .500 71.6 65.0
TRIBUTARY INFLOW 1017.9 99.2 .718E+05 100.0 .263 148.4 13.7
***TOTAL INFLOW 1026.3 100.0 .718E+05 100.0 .261 147.1 13.8
ADVECTIVE OUTFLOW 668.4 65.1 .407E+05 56.7 .302 97.9 9.0
***TOTAL OUTFLOW 668.4 65.1 .407E+05 56.7 .302 97.9 9.0
***RETENTION 358.0 34.9 .175E+05 24.3 .369 .0 .0
-------------------------------------------------------------------------------

HYDRAULIC -------------- TOTAL P --------------
OVERFLOW RESIDENCE POOL RESIDENCE TURNOVER RETENTION
RATE TIME CONC TIME RATIO COEF
M/YR YRS MG/M3 YRS - -
52.50 .0857 93.8 .0535 10.9605 .3488

GROSS MASS BALANCE BASED UPON ESTIMATED CONCENTRATIONS
COMPONENT: TOTAL N
----- LOADING ---- --- VARIANCE --- CONC EXPORT
ID T LOCATION KG/YR %(I) KG/YR**2 %(I) CV MG/M3 KG/KM2
-------------------------------------------------------------------------------
1 1 Roberson RC8 13375.1 99.5 .114E+08 100.0 .253 1949.7 180.2
-------------------------------------------------------------------------------
PRECIPITATION 69.7 .5 .121E+04 .0 .500 590.4 536.0
TRIBUTARY INFLOW 13375.1 99.5 .114E+08 100.0 .253 1949.7 180.2
***TOTAL INFLOW 13444.8 100.0 .114E+08 100.0 .251 1926.7 180.8
ADVECTIVE OUTFLOW 8903.1 66.2 .800E+07 70.0 .318 1304.5 119.7
***TOTAL OUTFLOW 8903.1 66.2 .800E+07 70.0 .318 1304.5 119.7
***RETENTION 4541.7 33.8 .404E+07 35.4 .443 .0 .0
-------------------------------------------------------------------------------

HYDRAULIC -------------- TOTAL N --------------
OVERFLOW RESIDENCE POOL RESIDENCE TURNOVER RETENTION
RATE TIME CONC TIME RATIO COEF
M/YR YRS MG/M3 YRS - -
52.50 .0857 1308.1 .0569 10.2957 .3378
CASE: Roberson Creek Cove 2001

WATER BALANCE TERMS (HM3/YR):

-------- INFLOWS -------- STORAGE --- OUTFLOWS --- DOWNSTR
SEG EXTERNAL PRECIP ADVECT INCREASE ADVECT DISCH EXCHANGE EVAP
---------------------------------------------------------------------------
1 .686E+01 .118E+00 .000E+00 .000E+00 .682E+01 .000E+00 .000E+00 .153E+00
---------------------------------------------------------------------------
NET .686E+01 .118E+00 .000E+00 .000E+00 .682E+01 .000E+00 .000E+00 .153E+00
---------------------------------------------------------------------------

MASS BALANCE TERMS (KG/YR) FOR: TOTAL P BASED UPON ESTIMATED CONCS:

--------- INFLOWS -------- STORAGE ---- OUTFLOWS---- NET NET
SEG EXTERNAL ATMOSP ADVECT INCREASE ADVECT DISCH EXCHANGE RETENT
---------------------------------------------------------------------------
Roberson (Robeson) Creek TMDL

1 .102E+04 .845E+01 .000E+00 .000E+00 .668E+03 .000E+00 .000E+00 .358E+03
---------------------------------------------------------------------------
NET .102E+04 .845E+01 .000E+00 .000E+00 .668E+03 .000E+00 .000E+00 .358E+03
---------------------------------------------------------------------------

MASS BALANCE TERMS (KG/YR) FOR: TOTAL N BASED UPON ESTIMATED CONCS:

--------- INFLOWS -------- STORAGE ---- OUTFLOWS---- NET NET
SEG EXTERNAL ATMOSP ADVECT INCREASE ADVECT DISCH EXCHANGE RETENT
---------------------------------------------------------------------------
1 .134E+05 .697E+02 .000E+00 .000E+00 .890E+04 .000E+00 .000E+00 .454E+04
---------------------------------------------------------------------------
NET .134E+05 .697E+02 .000E+00 .000E+00 .890E+04 .000E+00 .000E+00 .454E+04
---------------------------------------------------------------------------

Nutrient Balance Model Selection:

CASE: Roberson Creek Cove 2001

T STATISTICS COMPARE OBSERVED AND PREDICTED MEANS
USING THE FOLLOWING ERROR TERMS:
1 = OBSERVED WATER QUALITY ERROR ONLY
2 = ERROR TYPICAL OF MODEL DEVELOPMENT DATA SET
3 = OBSERVED AND PREDICTED ERROR

SEGMENT: 1 Roberson
OBSERVED ESTIMATED T STATISTICS
VARIABLE MEAN CV MEAN CV RATIO 1 2 3
-------------------------------------------------------------------------
TOTAL P MG/M3 93.8 .06 105.4 .20 .89 -1.95 -.43 -.56
TOTAL N MG/M3 1308.1 .08 1518.4 .20 .86 -1.86 -.68 -.69
C.NUTRIENT MG/M3 67.3 .07 77.4 .15 .87 -2.01 -.70 -.84
CHL-A MG/M3 32.9 .17 45.9 .32 .72 -1.96 -.96 -.91
SECCHI M .4 .13 .4 .20 1.13 .98 .44 .51
ORGANIC N MG/M3 876.2 .10 1330.4 .28 .66 -4.26 -1.67 -1.40
TP-ORTHO-P MG/M3 .0 .00 117.4 .28 .00 .00 .00 .00
-------------------------------------------------------------------------
CASE: Roberson Creek Cove 2001

T STATISTICS COMPARE OBSERVED AND PREDICTED MEANS
USING THE FOLLOWING ERROR TERMS:
1 = OBSERVED WATER QUALITY ERROR ONLY
2 = ERROR TYPICAL OF MODEL DEVELOPMENT DATA SET
3 = OBSERVED AND PREDICTED ERROR

SEGMENT: 1 Roberson
OBSERVED ESTIMATED T STATISTICS
VARIABLE MEAN CV MEAN CV RATIO 1 2 3
-------------------------------------------------------------------------
TOTAL P MG/M3 93.8 .06 97.9 .18 .96 -.72 -.16 -.22
TOTAL N MG/M3 1308.1 .08 1421.6 .17 .92 -1.04 -.38 -.43
C.NUTRIENT MG/M3 67.3 .07 71.9 .14 .94 -.96 -.33 -.44
Roberson (Robeson) Creek TMDL

CHL-A MG/M3 32.9 .17 41.9 .31 .79 -1.42 -.70 -.68
SECCHI M .4 .13 .4 .20 1.09 .69 .31 .37
ORGANIC N MG/M3 876.2 .10 1238.3 .27 .71 -3.53 -1.38 -1.21
TP-ORTHO-P MG/M3 .0 .00 110.2 .27 .00 .00 .00 .00
-------------------------------------------------------------------------
CASE: Roberson Creek Cove 2001

T STATISTICS COMPARE OBSERVED AND PREDICTED MEANS
USING THE FOLLOWING ERROR TERMS:
1 = OBSERVED WATER QUALITY ERROR ONLY
2 = ERROR TYPICAL OF MODEL DEVELOPMENT DATA SET
3 = OBSERVED AND PREDICTED ERROR

SEGMENT: 1 Roberson
OBSERVED ESTIMATED T STATISTICS
VARIABLE MEAN CV MEAN CV RATIO 1 2 3
-------------------------------------------------------------------------
TOTAL P MG/M3 93.8 .06 86.4 .19 1.09 1.37 .31 .42
TOTAL N MG/M3 1308.1 .08 1423.1 .17 .92 -1.05 -.38 -.44
C.NUTRIENT MG/M3 67.3 .07 67.0 .14 1.00 .06 .02 .03
CHL-A MG/M3 32.9 .17 38.3 .31 .86 -.90 -.44 -.43
SECCHI M .4 .13 .4 .20 1.05 .42 .19 .23
ORGANIC N MG/M3 876.2 .10 1157.3 .27 .76 -2.84 -1.11 -.98
TP-ORTHO-P MG/M3 .0 .00 103.9 .27 .00 .00 .00 .00
-------------------------------------------------------------------------
CASE: Roberson Creek Cove 2001

T STATISTICS COMPARE OBSERVED AND PREDICTED MEANS
USING THE FOLLOWING ERROR TERMS:
1 = OBSERVED WATER QUALITY ERROR ONLY
2 = ERROR TYPICAL OF MODEL DEVELOPMENT DATA SET
3 = OBSERVED AND PREDICTED ERROR

SEGMENT: 1 Roberson
OBSERVED ESTIMATED T STATISTICS
VARIABLE MEAN CV MEAN CV RATIO 1 2 3
-------------------------------------------------------------------------
TOTAL P MG/M3 93.8 .06 84.8 .23 1.11 1.68 .38 .42
TOTAL N MG/M3 1308.1 .08 1304.5 .22 1.00 .03 .01 .01
C.NUTRIENT MG/M3 67.3 .07 63.6 .17 1.06 .80 .28 .30
CHL-A MG/M3 32.9 .17 35.9 .34 .92 -.51 -.25 -.23
SECCHI M .4 .13 .4 .20 1.03 .24 .11 .12
ORGANIC N MG/M3 876.2 .10 1102.5 .28 .79 -2.34 -.92 -.78
TP-ORTHO-P MG/M3 .0 .00 99.6 .28 .00 .00 .00 .00
-------------------------------------------------------------------------
CASE: Roberson Creek Cove 2001

T STATISTICS COMPARE OBSERVED AND PREDICTED MEANS
USING THE FOLLOWING ERROR TERMS:
1 = OBSERVED WATER QUALITY ERROR ONLY
2 = ERROR TYPICAL OF MODEL DEVELOPMENT DATA SET
3 = OBSERVED AND PREDICTED ERROR

SEGMENT: 1 Roberson
OBSERVED ESTIMATED T STATISTICS
VARIABLE MEAN CV MEAN CV RATIO 1 2 3
Roberson (Robeson) Creek TMDL

-------------------------------------------------------------------------
TOTAL P MG/M3 93.8 .06 116.3 .20 .81 -3.59 -.80 -1.04
TOTAL N MG/M3 1308.1 .08 1602.4 .18 .82 -2.54 -.92 -1.01
C.NUTRIENT MG/M3 67.3 .07 83.9 .14 .80 -3.16 -1.10 -1.41
CHL-A MG/M3 32.9 .17 50.8 .31 .65 -2.55 -1.25 -1.21
SECCHI M .4 .13 .3 .20 1.18 1.31 .59 .69
ORGANIC N MG/M3 876.2 .10 1440.6 .28 .61 -5.07 -1.99 -1.68
TP-ORTHO-P MG/M3 .0 .00 126.0 .28 .00 .00 .00 .00
-------------------------------------------------------------------------
CASE: Roberson Creek Cove 2001

T STATISTICS COMPARE OBSERVED AND PREDICTED MEANS
USING THE FOLLOWING ERROR TERMS:
1 = OBSERVED WATER QUALITY ERROR ONLY
2 = ERROR TYPICAL OF MODEL DEVELOPMENT DATA SET
3 = OBSERVED AND PREDICTED ERROR

SEGMENT: 1 Roberson
OBSERVED ESTIMATED T STATISTICS
VARIABLE MEAN CV MEAN CV RATIO 1 2 3
-------------------------------------------------------------------------
TOTAL P MG/M3 93.8 .06 138.5 .17 .68 -6.50 -1.45 -2.13
TOTAL N MG/M3 1308.1 .08 1814.4 .16 .72 -4.09 -1.49 -1.84
C.NUTRIENT MG/M3 67.3 .07 98.0 .12 .69 -5.39 -1.87 -2.71
CHL-A MG/M3 32.9 .17 61.7 .30 .53 -3.69 -1.81 -1.82
SECCHI M .4 .13 .3 .20 1.29 2.02 .90 1.06
ORGANIC N MG/M3 876.2 .10 1689.5 .28 .52 -6.70 -2.63 -2.23
TP-ORTHO-P MG/M3 .0 .00 145.4 .28 .00 .00 .00 .00
-------------------------------------------------------------------------
CASE: Roberson Creek Cove 2001

T STATISTICS COMPARE OBSERVED AND PREDICTED MEANS
USING THE FOLLOWING ERROR TERMS:
1 = OBSERVED WATER QUALITY ERROR ONLY
2 = ERROR TYPICAL OF MODEL DEVELOPMENT DATA SET
3 = OBSERVED AND PREDICTED ERROR

SEGMENT: 1 Roberson
OBSERVED ESTIMATED T STATISTICS
VARIABLE MEAN CV MEAN CV RATIO 1 2 3
-------------------------------------------------------------------------
TOTAL P MG/M3 93.8 .06 147.6 .17 .64 -7.55 -1.68 -2.53
TOTAL N MG/M3 1308.1 .08 1933.1 .15 .68 -4.88 -1.78 -2.26
C.NUTRIENT MG/M3 67.3 .07 104.7 .12 .64 -6.34 -2.20 -3.27
CHL-A MG/M3 32.9 .17 67.0 .30 .49 -4.18 -2.05 -2.07
SECCHI M .4 .13 .3 .20 1.34 2.35 1.05 1.22
ORGANIC N MG/M3 876.2 .10 1810.6 .28 .48 -7.41 -2.90 -2.46
TP-ORTHO-P MG/M3 .0 .00 154.9 .28 .00 .00 .00 .00
-------------------------------------------------------------------------

Chlorophyll a Model Selection:

CASE: Roberson Creek Cove 2001

Roberson (Robeson) Creek TMDL

T STATISTICS COMPARE OBSERVED AND PREDICTED MEANS
USING THE FOLLOWING ERROR TERMS:
1 = OBSERVED WATER QUALITY ERROR ONLY
2 = ERROR TYPICAL OF MODEL DEVELOPMENT DATA SET
3 = OBSERVED AND PREDICTED ERROR

SEGMENT: 1 Roberson
OBSERVED ESTIMATED T STATISTICS
VARIABLE MEAN CV MEAN CV RATIO 1 2 3
-------------------------------------------------------------------------
TOTAL P MG/M3 93.8 .06 97.9 .18 .96 -.72 -.16 -.22
TOTAL N MG/M3 1308.1 .08 1304.5 .22 1.00 .03 .01 .01
C.NUTRIENT MG/M3 67.3 .07 68.6 .16 .98 -.29 -.10 -.12
CHL-A MG/M3 32.9 .17 12.3 .30 2.69 5.81 2.86 2.86
SECCHI M .4 .13 .5 .19 .79 -1.85 -.83 -1.03
ORGANIC N MG/M3 876.2 .10 562.7 .18 1.56 4.52 1.77 2.13
TP-ORTHO-P MG/M3 .0 .00 57.5 .21 .00 .00 .00 .00
-------------------------------------------------------------------------
CASE: Roberson Creek Cove 2001

T STATISTICS COMPARE OBSERVED AND PREDICTED MEANS
USING THE FOLLOWING ERROR TERMS:
1 = OBSERVED WATER QUALITY ERROR ONLY
2 = ERROR TYPICAL OF MODEL DEVELOPMENT DATA SET
3 = OBSERVED AND PREDICTED ERROR

SEGMENT: 1 Roberson
OBSERVED ESTIMATED T STATISTICS
VARIABLE MEAN CV MEAN CV RATIO 1 2 3
-------------------------------------------------------------------------
TOTAL P MG/M3 93.8 .06 97.9 .18 .96 -.72 -.16 -.22
TOTAL N MG/M3 1308.1 .08 1304.5 .22 1.00 .03 .01 .01
C.NUTRIENT MG/M3 67.3 .07 68.6 .16 .98 -.29 -.10 -.12
CHL-A MG/M3 32.9 .17 10.8 .30 3.06 6.58 3.23 3.25
SECCHI M .4 .13 .5 .19 .78 -2.00 -.89 -1.11
ORGANIC N MG/M3 876.2 .10 528.5 .17 1.66 5.16 2.02 2.53
TP-ORTHO-P MG/M3 .0 .00 54.8 .21 .00 .00 .00 .00
-------------------------------------------------------------------------
CASE: Roberson Creek Cove 2001

T STATISTICS COMPARE OBSERVED AND PREDICTED MEANS
USING THE FOLLOWING ERROR TERMS:
1 = OBSERVED WATER QUALITY ERROR ONLY
2 = ERROR TYPICAL OF MODEL DEVELOPMENT DATA SET
3 = OBSERVED AND PREDICTED ERROR

SEGMENT: 1 Roberson
OBSERVED ESTIMATED T STATISTICS
VARIABLE MEAN CV MEAN CV RATIO 1 2 3
-------------------------------------------------------------------------
TOTAL P MG/M3 93.8 .06 97.9 .18 .96 -.72 -.16 -.22
TOTAL N MG/M3 1308.1 .08 1304.5 .22 1.00 .03 .01 .01
C.NUTRIENT MG/M3 67.3 .07 68.6 .16 .98 -.29 -.10 -.12
CHL-A MG/M3 32.9 .17 39.5 .33 .83 -1.07 -.53 -.50
SECCHI M .4 .13 .4 .20 1.07 .51 .23 .27
ORGANIC N MG/M3 876.2 .10 1184.0 .28 .74 -3.07 -1.20 -1.03
Roberson (Robeson) Creek TMDL

TP-ORTHO-P MG/M3 .0 .00 106.0 .27 .00 .00 .00 .00
-------------------------------------------------------------------------
CASE: Roberson Creek Cove 2001

T STATISTICS COMPARE OBSERVED AND PREDICTED MEANS
USING THE FOLLOWING ERROR TERMS:
1 = OBSERVED WATER QUALITY ERROR ONLY
2 = ERROR TYPICAL OF MODEL DEVELOPMENT DATA SET
3 = OBSERVED AND PREDICTED ERROR

SEGMENT: 1 Roberson
OBSERVED ESTIMATED T STATISTICS
VARIABLE MEAN CV MEAN CV RATIO 1 2 3
-------------------------------------------------------------------------
TOTAL P MG/M3 93.8 .06 97.9 .18 .96 -.72 -.16 -.22
TOTAL N MG/M3 1308.1 .08 1304.5 .22 1.00 .03 .01 .01
C.NUTRIENT MG/M3 67.3 .07 68.6 .16 .98 -.29 -.10 -.12
CHL-A MG/M3 32.9 .17 27.4 .32 1.20 1.08 .53 .51
SECCHI M .4 .13 .4 .20 .95 -.45 -.20 -.24
ORGANIC N MG/M3 876.2 .10 908.5 .25 .96 -.37 -.14 -.13
TP-ORTHO-P MG/M3 .0 .00 84.5 .26 .00 .00 .00 .00
-------------------------------------------------------------------------
CASE: Roberson Creek Cove 2001

T STATISTICS COMPARE OBSERVED AND PREDICTED MEANS
USING THE FOLLOWING ERROR TERMS:
1 = OBSERVED WATER QUALITY ERROR ONLY
2 = ERROR TYPICAL OF MODEL DEVELOPMENT DATA SET
3 = OBSERVED AND PREDICTED ERROR

SEGMENT: 1 Roberson
OBSERVED ESTIMATED T STATISTICS
VARIABLE MEAN CV MEAN CV RATIO 1 2 3
-------------------------------------------------------------------------
TOTAL P MG/M3 93.8 .06 97.9 .18 .96 -.72 -.16 -.22
TOTAL N MG/M3 1308.1 .08 1304.5 .22 1.00 .03 .01 .01
C.NUTRIENT MG/M3 67.3 .07 68.6 .16 .98 -.29 -.10 -.12
CHL-A MG/M3 32.9 .17 65.3 .37 .50 -4.03 -1.98 -1.67
SECCHI M .4 .13 .3 .23 1.32 2.25 1.00 1.07
ORGANIC N MG/M3 876.2 .10 1773.1 .34 .49 -7.19 -2.82 -2.01
TP-ORTHO-P MG/M3 .0 .00 152.0 .33 .00 .00 .00 .00
-------------------------------------------------------------------------

Calibrated Model:

Roberson Creek Cove 2001

MODEL OPTIONS:
1 CONSERVATIVE SUBSTANCE 0 NOT COMPUTED
2 PHOSPHORUS BALANCE 2 2ND ORDER, DECAY
3 NITROGEN BALANCE 4 BACHMAN VOL. LOAD
4 CHLOROPHYLL-A 3 P, N, LOW-TURBIDITY
5 SECCHI DEPTH 1 VS. CHLA & TURBIDITY
6 DISPERSION 1 FISCHER-NUMERIC
7 PHOSPHORUS CALIBRATION 1 DECAY RATES
Roberson (Robeson) Creek TMDL

8 NITROGEN CALIBRATION 1 DECAY RATES
9 ERROR ANALYSIS 1 MODEL & DATA
10 AVAILABILITY FACTORS 1 USE FOR MODEL 1 ONLY
11 MASS-BALANCE TABLES 1 USE ESTIMATED CONCS

ATMOSPHERIC LOADS & AVAILABILITY FACTORS:
ATMOSPHERIC-LOADS AVAILABILITY
VARIABLE KG/KM2-YR CV FACTOR
1 CONSERV .00 .00 .00
2 TOTAL P 65.00 .50 1.33
3 TOTAL N 536.00 .50 .59
4 ORTHO P 32.50 .50 .33
5 INORG N 359.00 .50 .79

GLOBAL INPUT VALUES:
PARAMETER MEAN CV
PERIOD LENGTH YRS .586 .000
PRECIPITATION M .532 .200
EVAPORATION M .690 .300
INCREASE IN STORAGE M .000 .000

TRIBUTARY DRAINAGE AREAS AND FLOWS:
ID TYPE SEG NAME DRAINAGE AREA MEAN FLOW CV OF MEAN FLOW
KM2 HM3/YR
1 1 1 Roberson RC8 74.240 6.860 .201

TRIBUTARY CONCENTRATIONS (PPB): MEAN/CV
ID CONSERV TOTAL P TOTAL N ORTHO P INORG N
1 .0/ .00 148.4/ .17 1949.7/ .15 103.9/ .17 1426.4/ .23

MODEL SEGMENTS & CALIBRATION FACTORS:
----------- CALIBRATION FACTORS -----------
SEG OUTFLOW GROUP SEGMENT NAME P SED N SED CHL-A SECCHI HOD DISP
1 0 1 Roberson 1.00 1.00 1.00 1.00 1.00 1.000
CV: .000 .000 .000 .000 .000 .000

SEGMENT MORPHOMETRY: MEAN/CV
LENGTH AREA ZMEAN ZMIX ZHYP
ID LABEL KM KM2 M M M
1 Roberson 1.75 .1300 4.50 4.24/ .00 .00/ .00

SEGMENT OBSERVED WATER QUALITY:
SEG TURBID CONSER TOTALP TOTALN CHL-A SECCHI ORG-N TP-OP HODV MODV
1/M --- MG/M3 MG/M3 MG/M3 M MG/M3 MG/M3 MG/M3-D MG/M3-D
1 MN: .00 .0 93.8 1308.1 32.9 .4 876.2 .0 .0 .0
CV: .00 .00 .06 .08 .17 .13 .10 .00 .00 .00

MODEL COEFFICIENTS:
COEFFICIENT MEAN CV
DISPERSION FACTO 1.000 .70
P DECAY RATE 1.000 .45
N DECAY RATE 1.000 .55
CHL-A MODEL .830 .26
SECCHI MODEL 1.000 .10
ORGANIC N MODEL .830 .12
TP-OP MODEL 1.000 .15
Roberson (Robeson) Creek TMDL

HODV MODEL 1.000 .15
MODV MODEL 1.000 .22
BETA M2/MG .025 .00
MINIMUM QS 4.000 .00
FLUSHING EFFECT 1.000 .00
CHLOROPHYLL-A CV .620 .00

CASE NOTES:
single reservoir

spatially averaged

Calibrated Model Results:

CASE: Roberson Creek Cove 2001

T STATISTICS COMPARE OBSERVED AND PREDICTED MEANS
USING THE FOLLOWING ERROR TERMS:
1 = OBSERVED WATER QUALITY ERROR ONLY
2 = ERROR TYPICAL OF MODEL DEVELOPMENT DATA SET
3 = OBSERVED AND PREDICTED ERROR

SEGMENT: 1 Roberson
OBSERVED ESTIMATED T STATISTICS
VARIABLE MEAN CV MEAN CV RATIO 1 2 3
-------------------------------------------------------------------------
TOTAL P MG/M3 93.8 .06 97.9 .18 .96 -.72 -.16 -.22
TOTAL N MG/M3 1308.1 .08 1304.5 .22 1.00 .03 .01 .01
C.NUTRIENT MG/M3 67.3 .07 68.6 .16 .98 -.29 -.10 -.12
CHL-A MG/M3 32.9 .17 32.8 .33 1.00 .02 .01 .01
SECCHI M .4 .13 .4 .20 1.00 -.01 .00 -.01
ORGANIC N MG/M3 876.2 .10 855.6 .27 1.02 .24 .09 .08
TP-ORTHO-P MG/M3 .0 .00 94.0 .27 .00 .00 .00 .00
-------------------------------------------------------------------------
CASE: Roberson Creek Cove 2001

OBSERVED AND PREDICTED DIAGNOSTIC VARIABLES
RANKED AGAINST CE MODEL DEVELOPMENT DATA SET

SEGMENT: 1 Roberson
----- VALUES ----- --- RANKS (%) ----
VARIABLE OBSERVED ESTIMATED OBSERVED ESTIMATED
--------------------------------------------------------
TOTAL P MG/M3 93.80 97.93 77.2 78.7
TOTAL N MG/M3 1308.10 1304.49 66.2 66.0
C.NUTRIENT MG/M3 67.26 68.63 78.6 79.3
CHL-A MG/M3 32.92 32.79 94.8 94.8
SECCHI M .40 .40 9.6 9.6
ORGANIC N MG/M3 876.20 855.65 88.6 87.7
TP-ORTHO-P MG/M3 .00 94.01 .0 88.5
ANTILOG PC-1 1416.73 1417.30 91.0 91.0
ANTILOG PC-2 7.56 7.49 62.1 61.4
(N - 150) / P 12.35 11.79 31.9 29.5
Roberson (Robeson) Creek TMDL

INORGANIC N / P .00 114.59 .0 91.3
TURBIDITY 1/M 1.68 1.68 87.5 87.5
ZMIX * TURBIDITY 7.11 7.11 85.3 85.3
ZMIX / SECCHI 10.59 10.58 91.5 91.4
CHL-A * SECCHI 13.17 13.13 64.1 63.9
CHL-A / TOTAL P .35 .33 82.0 80.0
FREQ(CHL-a>10) % 94.65 94.58 .0 .0
FREQ(CHL-a>20) % 68.93 68.71 .0 .0
FREQ(CHL-a>30) % 43.63 43.38 .0 .0
FREQ(CHL-a>40) % 26.62 26.41 .0 .0
FREQ(CHL-a>50) % 16.25 16.09 .0 .0
FREQ(CHL-a>60) % 10.06 9.95 .0 .0
CARLSON TSI-P 69.63 70.25 .0 .0
CARLSON TSI-CHLA 64.88 64.84 .0 .0
CARLSON TSI-SEC 73.20 73.19 .0 .0
--------------------------------------------------------

Roberson (Robeson) Creek TMDL

Appendix IX. BATHTUB verification files.

Verification - Apr-Oct

Roberson Creek Cove 2002

MODEL OPTIONS:
1 CONSERVATIVE SUBSTANCE 0 NOT COMPUTED
2 PHOSPHORUS BALANCE 2 2ND ORDER, DECAY
3 NITROGEN BALANCE 4 BACHMAN VOL. LOAD
4 CHLOROPHYLL-A 3 P, N, LOW-TURBIDITY
5 SECCHI DEPTH 1 VS. CHLA & TURBIDITY
6 DISPERSION 1 FISCHER-NUMERIC
7 PHOSPHORUS CALIBRATION 1 DECAY RATES
8 NITROGEN CALIBRATION 1 DECAY RATES
9 ERROR ANALYSIS 1 MODEL & DATA
10 AVAILABILITY FACTORS 1 USE FOR MODEL 1 ONLY
11 MASS-BALANCE TABLES 1 USE ESTIMATED CONCS

ATMOSPHERIC LOADS & AVAILABILITY FACTORS:
ATMOSPHERIC-LOADS AVAILABILITY
VARIABLE KG/KM2-YR CV FACTOR
1 CONSERV .00 .00 .00
2 TOTAL P 65.00 .50 1.33
3 TOTAL N 536.00 .50 .59
4 ORTHO P 32.50 .50 .33
5 INORG N 359.00 .50 .79

GLOBAL INPUT VALUES:
PARAMETER MEAN CV
PERIOD LENGTH YRS .586 .000
PRECIPITATION M .607 .200
EVAPORATION M .683 .300
INCREASE IN STORAGE M .000 .000

TRIBUTARY DRAINAGE AREAS AND FLOWS:
ID TYPE SEG NAME DRAINAGE AREA MEAN FLOW CV OF MEAN FLOW
KM2 HM3/YR
1 1 1 Roberson 74.240 7.220 .560

TRIBUTARY CONCENTRATIONS (PPB): MEAN/CV
ID CONSERV TOTAL P TOTAL N ORTHO P INORG N
1 .0/ .00 166.4/ .17 2368.6/ .15 116.5/ .17 1915.4/ .18

MODEL SEGMENTS & CALIBRATION FACTORS:
----------- CALIBRATION FACTORS -----------
SEG OUTFLOW GROUP SEGMENT NAME P SED N SED CHL-A SECCHI HOD DISP
1 0 1 Roberson 1.00 1.00 1.00 1.00 1.00 1.000
CV: .000 .000 .000 .000 .000 .000

SEGMENT MORPHOMETRY: MEAN/CV
LENGTH AREA ZMEAN ZMIX ZHYP
ID LABEL KM KM2 M M M
1 Roberson 1.75 .1300 3.20 3.20/ .00 .00/ .00

Roberson (Robeson) Creek TMDL

SEGMENT OBSERVED WATER QUALITY:
SEG TURBID CONSER TOTALP TOTALN CHL-A SECCHI ORG-N TP-OP HODV MODV
1/M --- MG/M3 MG/M3 MG/M3 M MG/M3 MG/M3 MG/M3-D MG/M3-D
1 MN: .00 .0 106.7 1217.9 39.1 .4 720.2 .0 .0 .0
CV: .00 .00 .06 .08 .17 .10 .14 .00 .00 .00

MODEL COEFFICIENTS:
COEFFICIENT MEAN CV
DISPERSION FACTO 1.000 .70
P DECAY RATE 1.000 .45
N DECAY RATE 1.000 .55
CHL-A MODEL .830 .26
SECCHI MODEL 1.000 .10
ORGANIC N MODEL .830 .12
TP-OP MODEL 1.000 .15
HODV MODEL 1.000 .15
MODV MODEL 1.000 .22
BETA M2/MG .025 .00
MINIMUM QS 4.000 .00
FLUSHING EFFECT 1.000 .00
CHLOROPHYLL-A CV .620 .00

CASE NOTES:
single reservoir

spatially averaged

CASE: Roberson Creek Cove 2002

T STATISTICS COMPARE OBSERVED AND PREDICTED MEANS
USING THE FOLLOWING ERROR TERMS:
1 = OBSERVED WATER QUALITY ERROR ONLY
2 = ERROR TYPICAL OF MODEL DEVELOPMENT DATA SET
3 = OBSERVED AND PREDICTED ERROR

SEGMENT: 1 Roberson
OBSERVED ESTIMATED T STATISTICS
VARIABLE MEAN CV MEAN CV RATIO 1 2 3
-------------------------------------------------------------------------
TOTAL P MG/M3 106.7 .06 117.0 .20 .91 -1.62 -.34 -.45
TOTAL N MG/M3 1217.9 .08 1604.7 .22 .76 -3.63 -1.25 -1.16
C.NUTRIENT MG/M3 68.3 .07 84.2 .17 .81 -3.09 -1.04 -1.14
CHL-A MG/M3 39.1 .17 42.3 .34 .92 -.46 -.23 -.21
SECCHI M .4 .10 .4 .20 1.03 .29 .10 .13
ORGANIC N MG/M3 720.2 .14 1040.5 .29 .69 -2.67 -1.47 -1.16
TP-ORTHO-P MG/M3 .0 .00 112.6 .28 .00 .00 .00 .00
-------------------------------------------------------------------------
Roberson (Robeson) Creek TMDL

Verification - Apr-Sept

Roberson Creek Cove 2002

MODEL OPTIONS:
1 CONSERVATIVE SUBSTANCE 0 NOT COMPUTED
2 PHOSPHORUS BALANCE 2 2ND ORDER, DECAY
3 NITROGEN BALANCE 4 BACHMAN VOL. LOAD
4 CHLOROPHYLL-A 3 P, N, LOW-TURBIDITY
5 SECCHI DEPTH 1 VS. CHLA & TURBIDITY
6 DISPERSION 1 FISCHER-NUMERIC
7 PHOSPHORUS CALIBRATION 1 DECAY RATES
8 NITROGEN CALIBRATION 1 DECAY RATES
9 ERROR ANALYSIS 1 MODEL & DATA
10 AVAILABILITY FACTORS 1 USE FOR MODEL 1 ONLY
11 MASS-BALANCE TABLES 1 USE ESTIMATED CONCS

ATMOSPHERIC LOADS & AVAILABILITY FACTORS:
ATMOSPHERIC-LOADS AVAILABILITY
VARIABLE KG/KM2-YR CV FACTOR
1 CONSERV .00 .00 .00
2 TOTAL P 65.00 .50 1.33
3 TOTAL N 536.00 .50 .59
4 ORTHO P 32.50 .50 .33
5 INORG N 359.00 .50 .79

GLOBAL INPUT VALUES:
PARAMETER MEAN CV
PERIOD LENGTH YRS .501 .000
PRECIPITATION M .480 .200
EVAPORATION M .501 .300
INCREASE IN STORAGE M .000 .000

TRIBUTARY DRAINAGE AREAS AND FLOWS:
ID TYPE SEG NAME DRAINAGE AREA MEAN FLOW CV OF MEAN FLOW
KM2 HM3/YR
1 1 1 Roberson 74.240 2.225 .300

TRIBUTARY CONCENTRATIONS (PPB): MEAN/CV
ID CONSERV TOTAL P TOTAL N ORTHO P INORG N
1 .0/ .00 166.4/ .17 2368.6/ .15 116.5/ .17 1915.4/ .18

MODEL SEGMENTS & CALIBRATION FACTORS:
----------- CALIBRATION FACTORS -----------
SEG OUTFLOW GROUP SEGMENT NAME P SED N SED CHL-A SECCHI HOD DISP
1 0 1 Roberson 1.00 1.00 1.00 1.00 1.00 1.000
CV: .000 .000 .000 .000 .000 .000

SEGMENT MORPHOMETRY: MEAN/CV
LENGTH AREA ZMEAN ZMIX ZHYP
ID LABEL KM KM2 M M M
1 Roberson 1.75 .1300 3.20 3.20/ .00 .00/ .00

SEGMENT OBSERVED WATER QUALITY:
Roberson (Robeson) Creek TMDL

SEG TURBID CONSER TOTALP TOTALN CHL-A SECCHI ORG-N TP-OP HODV MODV
1/M --- MG/M3 MG/M3 MG/M3 M MG/M3 MG/M3 MG/M3-D MG/M3-D
1 MN: .00 .0 105.5 1215.9 41.7 .4 743.0 .0 .0 .0
CV: .00 .00 .17 .08 .16 .10 .14 .00 .00 .00

MODEL COEFFICIENTS:
COEFFICIENT MEAN CV
DISPERSION FACTO 1.000 .70
P DECAY RATE 1.000 .45
N DECAY RATE 1.000 .55
CHL-A MODEL .830 .26
SECCHI MODEL 1.000 .10
ORGANIC N MODEL .830 .12
TP-OP MODEL 1.000 .15
HODV MODEL 1.000 .15
MODV MODEL 1.000 .22
BETA M2/MG .025 .00
MINIMUM QS 4.000 .00
FLUSHING EFFECT 1.000 .00
CHLOROPHYLL-A CV .620 .00

CASE NOTES:
single reservoir

spatially averaged

CASE: Roberson Creek Cove 2002

T STATISTICS COMPARE OBSERVED AND PREDICTED MEANS
USING THE FOLLOWING ERROR TERMS:
1 = OBSERVED WATER QUALITY ERROR ONLY
2 = ERROR TYPICAL OF MODEL DEVELOPMENT DATA SET
3 = OBSERVED AND PREDICTED ERROR

SEGMENT: 1 Roberson
OBSERVED ESTIMATED T STATISTICS
VARIABLE MEAN CV MEAN CV RATIO 1 2 3
-------------------------------------------------------------------------
TOTAL P MG/M3 105.5 .17 94.8 .20 1.11 .63 .40 .41
TOTAL N MG/M3 1215.9 .08 1343.3 .27 .91 -1.25 -.45 -.36
C.NUTRIENT MG/M3 67.9 .12 68.6 .18 .99 -.08 -.05 -.05
CHL-A MG/M3 41.7 .16 32.8 .34 1.27 1.54 .69 .63
SECCHI M .4 .10 .4 .20 .92 -.86 -.31 -.39
ORGANIC N MG/M3 743.0 .14 854.6 .28 .87 -1.00 -.56 -.45
TP-ORTHO-P MG/M3 .0 .00 93.6 .27 .00 .00 .00 .00
-------------------------------------------------------------------------
CASE: Roberson Creek Cove 2002

OBSERVED AND PREDICTED DIAGNOSTIC VARIABLES
RANKED AGAINST CE MODEL DEVELOPMENT DATA SET

SEGMENT: 1 Roberson
----- VALUES ----- --- RANKS (%) ----
Roberson (Robeson) Creek TMDL

VARIABLE OBSERVED ESTIMATED OBSERVED ESTIMATED
--------------------------------------------------------
TOTAL P MG/M3 105.50 94.84 81.0 77.6
TOTAL N MG/M3 1215.90 1343.26 61.9 67.7
C.NUTRIENT MG/M3 67.95 68.63 78.9 79.3
CHL-A MG/M3 41.68 32.79 97.4 94.8
SECCHI M .37 .40 7.9 9.7
ORGANIC N MG/M3 743.00 854.62 81.1 87.6
TP-ORTHO-P MG/M3 .00 93.62 .0 88.5
ANTILOG PC-1 1588.40 1412.26 92.3 90.9
ANTILOG PC-2 8.20 7.52 67.8 61.7
(N - 150) / P 10.10 12.58 22.2 32.9
INORGANIC N / P .00 403.43 .0 99.6
TURBIDITY 1/M 1.66 1.66 87.3 87.3
ZMIX * TURBIDITY 5.31 5.31 75.0 75.0
ZMIX / SECCHI 8.65 7.94 84.7 80.9
CHL-A * SECCHI 15.42 13.22 72.0 64.3
CHL-A / TOTAL P .40 .35 86.5 81.4
FREQ(CHL-a>10) % 97.68 94.58 .0 .0
FREQ(CHL-a>20) % 80.91 68.71 .0 .0
FREQ(CHL-a>30) % 58.73 43.38 .0 .0
FREQ(CHL-a>40) % 40.37 26.41 .0 .0
FREQ(CHL-a>50) % 27.30 16.09 .0 .0
FREQ(CHL-a>60) % 18.47 9.94 .0 .0
CARLSON TSI-P 71.33 69.79 .0 .0
CARLSON TSI-CHLA 67.19 64.84 .0 .0
CARLSON TSI-SEC 74.33 73.09 .0 .0
--------------------------------------------------------

Roberson (Robeson) Creek TMDL

Appendix X. BATHTUB phosphorus loading scenarios.

Roberson Creek Cove 2001

MODEL OPTIONS:
1 CONSERVATIVE SUBSTANCE 0 NOT COMPUTED
2 PHOSPHORUS BALANCE 2 2ND ORDER, DECAY
3 NITROGEN BALANCE 4 BACHMAN VOL. LOAD
4 CHLOROPHYLL-A 3 P, N, LOW-TURBIDITY
5 SECCHI DEPTH 1 VS. CHLA & TURBIDITY
6 DISPERSION 1 FISCHER-NUMERIC
7 PHOSPHORUS CALIBRATION 1 DECAY RATES
8 NITROGEN CALIBRATION 1 DECAY RATES
9 ERROR ANALYSIS 0 NOT COMPUTED
10 AVAILABILITY FACTORS 1 USE FOR MODEL 1 ONLY
11 MASS-BALANCE TABLES 1 USE ESTIMATED CONCS

ATMOSPHERIC LOADS & AVAILABILITY FACTORS:
ATMOSPHERIC-LOADS AVAILABILITY
VARIABLE KG/KM2-YR CV FACTOR
1 CONSERV .00 .00 .00
2 TOTAL P 65.00 .50 1.33
3 TOTAL N 536.00 .50 .59
4 ORTHO P 32.50 .50 .33
5 INORG N 359.00 .50 .79

GLOBAL INPUT VALUES:
PARAMETER MEAN CV
PERIOD LENGTH YRS .586 .000
PRECIPITATION M .532 .200
EVAPORATION M .690 .300
INCREASE IN STORAGE M .000 .000

TRIBUTARY DRAINAGE AREAS AND FLOWS:
ID TYPE SEG NAME DRAINAGE AREA MEAN FLOW CV OF MEAN FLOW
KM2 HM3/YR
1 1 1 -70.7% 74.240 6.860 .201
2 1 2 -49.6% 74.240 6.860 .201
3 1 3 -87.5% 74.240 6.860 .201
4 1 4 -25% 74.240 6.860 .201
5 1 5 -39% 74.240 6.860 .201
6 1 6 -0% 74.240 6.860 .201

TRIBUTARY CONCENTRATIONS (PPB): MEAN/CV
ID CONSERV TOTAL P TOTAL N ORTHO P INORG N
1 .0/ .00 43.5/ .00 1949.7/ .00 30.4/ .00 1426.4/ .00
2 .0/ .00 74.8/ .00 1949.7/ .00 52.4/ .00 1426.4/ .00
3 .0/ .00 18.6/ .00 1949.7/ .00 13.0/ .00 1426.4/ .00
4 .0/ .00 111.3/ .00 1949.7/ .00 77.9/ .00 1426.4/ .00
5 .0/ .00 90.5/ .00 1949.7/ .00 63.4/ .00 1426.4/ .00
6 .0/ .00 148.4/ .00 1949.7/ .00 103.9/ .00 1426.4/ .00

MODEL SEGMENTS & CALIBRATION FACTORS:
----------- CALIBRATION FACTORS -----------
SEG OUTFLOW GROUP SEGMENT NAME P SED N SED CHL-A SECCHI HOD DISP
Roberson (Robeson) Creek TMDL

1 0 1 TP -70.7% 1.00 1.00 1.00 1.00 1.00 1.000
CV: .000 .000 .000 .000 .000 .000
2 0 1 TP -49.6% 1.00 1.00 1.00 1.00 1.00 1.000
CV: .000 .000 .000 .000 .000 .000
3 0 1 TP -87.5% 1.00 1.00 1.00 1.00 1.00 1.000
CV: .000 .000 .000 .000 .000 .000
4 0 1 TP -25% 1.00 1.00 1.00 1.00 1.00 1.000
CV: .000 .000 .000 .000 .000 .000
5 0 1 TP -39% 1.00 1.00 1.00 1.00 1.00 1.000
CV: .000 .000 .000 .000 .000 .000
6 0 1 2001 Condition 1.00 1.00 1.00 1.00 1.00 1.000
CV: .000 .000 .000 .000 .000 .000

SEGMENT MORPHOMETRY: MEAN/CV
LENGTH AREA ZMEAN ZMIX ZHYP
ID LABEL KM KM2 M M M
1 TP -70.7% 1.75 .1300 4.50 4.20/ .00 .00/ .00
2 TP -49.6% 1.75 .1300 4.50 4.20/ .00 .00/ .00
3 TP -87.5% 1.75 .1300 4.50 4.20/ .00 .00/ .00
4 TP -25% 1.75 .1300 4.50 4.20/ .00 .00/ .00
5 TP -39% 1.75 .1300 4.50 4.20/ .00 .00/ .00
6 2001 Condition 1.75 .1300 4.50 4.20/ .00 .00/ .00

SEGMENT OBSERVED WATER QUALITY:
SEG TURBID CONSER TOTALP TOTALN CHL-A SECCHI ORG-N TP-OP HODV MODV
1/M --- MG/M3 MG/M3 MG/M3 M MG/M3 MG/M3 MG/M3-D MG/M3-D
1 MN: .00 .0 .0 .0 .0 .0 .0 .0 .0 .0
CV: .00 .00 .00 .00 .00 .00 .00 .00 .00 .00
2 MN: .00 .0 .0 .0 .0 .0 .0 .0 .0 .0
CV: .00 .00 .00 .00 .00 .00 .00 .00 .00 .00
3 MN: .00 .0 .0 .0 .0 .0 .0 .0 .0 .0
CV: .00 .00 .00 .00 .00 .00 .00 .00 .00 .00
4 MN: .00 .0 .0 .0 .0 .0 .0 .0 .0 .0
CV: .00 .00 .00 .00 .00 .00 .00 .00 .00 .00
5 MN: .00 .0 .0 .0 .0 .0 .0 .0 .0 .0
CV: .00 .00 .00 .00 .00 .00 .00 .00 .00 .00
6 MN: .00 .0 .0 .0 .0 .0 .0 .0 .0 .0
CV: .00 .00 .00 .00 .00 .00 .00 .00 .00 .00

MODEL COEFFICIENTS:
COEFFICIENT MEAN CV
DISPERSION FACTO 1.000 .70
P DECAY RATE 1.000 .45
N DECAY RATE 1.000 .55
CHL-A MODEL .830 .26
SECCHI MODEL 1.000 .10
ORGANIC N MODEL .830 .12
TP-OP MODEL 1.000 .15
HODV MODEL 1.000 .15
MODV MODEL 1.000 .22
BETA M2/MG .025 .00
MINIMUM QS 4.000 .00
FLUSHING EFFECT 1.000 .00
CHLOROPHYLL-A CV .620 .00

Roberson (Robeson) Creek TMDL

CASE: Roberson Creek Cove 2001

T STATISTICS COMPARE OBSERVED AND PREDICTED MEANS
USING THE FOLLOWING ERROR TERMS:
1 = OBSERVED WATER QUALITY ERROR ONLY
2 = ERROR TYPICAL OF MODEL DEVELOPMENT DATA SET
3 = OBSERVED AND PREDICTED ERROR

SEGMENT: 1 TP -70.7%
OBSERVED ESTIMATED T STATISTICS
VARIABLE MEAN CV MEAN CV RATIO 1 2 3
-------------------------------------------------------------------------
TOTAL P MG/M3 .0 .00 37.3 .07 .00 .00 .00 .00
TOTAL N MG/M3 .0 .00 1304.5 .19 .00 .00 .00 .00
C.NUTRIENT MG/M3 .0 .00 34.8 .07 .00 .00 .00 .00
CHL-A MG/M3 .0 .00 14.0 .27 .00 .00 .00 .00
-------------------------------------------------------------------------

SEGMENT: 2 TP -49.6%
OBSERVED ESTIMATED T STATISTICS
VARIABLE MEAN CV MEAN CV RATIO 1 2 3
-------------------------------------------------------------------------
TOTAL P MG/M3 .0 .00 58.0 .09 .00 .00 .00 .00
TOTAL N MG/M3 .0 .00 1304.5 .19 .00 .00 .00 .00
C.NUTRIENT MG/M3 .0 .00 49.7 .10 .00 .00 .00 .00
CHL-A MG/M3 .0 .00 21.9 .29 .00 .00 .00 .00
-------------------------------------------------------------------------

SEGMENT: 3 TP -87.5%
OBSERVED ESTIMATED T STATISTICS
VARIABLE MEAN CV MEAN CV RATIO 1 2 3
-------------------------------------------------------------------------
TOTAL P MG/M3 .0 .00 18.1 .05 .00 .00 .00 .00
TOTAL N MG/M3 .0 .00 1304.5 .19 .00 .00 .00 .00
C.NUTRIENT MG/M3 .0 .00 17.8 .05 .00 .00 .00 .00
CHL-A MG/M3 .0 .00 6.1 .27 .00 .00 .00 .00
-------------------------------------------------------------------------

SEGMENT: 4 TP -25%
OBSERVED ESTIMATED T STATISTICS
VARIABLE MEAN CV MEAN CV RATIO 1 2 3
-------------------------------------------------------------------------
TOTAL P MG/M3 .0 .00 79.0 .11 .00 .00 .00 .00
TOTAL N MG/M3 .0 .00 1304.5 .19 .00 .00 .00 .00
C.NUTRIENT MG/M3 .0 .00 61.0 .12 .00 .00 .00 .00
CHL-A MG/M3 .0 .00 28.3 .30 .00 .00 .00 .00
-------------------------------------------------------------------------

SEGMENT: 5 TP -39%
OBSERVED ESTIMATED T STATISTICS
VARIABLE MEAN CV MEAN CV RATIO 1 2 3
-------------------------------------------------------------------------
TOTAL P MG/M3 .0 .00 67.4 .10 .00 .00 .00 .00
TOTAL N MG/M3 .0 .00 1304.5 .19 .00 .00 .00 .00
C.NUTRIENT MG/M3 .0 .00 55.2 .11 .00 .00 .00 .00
CHL-A MG/M3 .0 .00 25.0 .29 .00 .00 .00 .00
Roberson (Robeson) Creek TMDL

-------------------------------------------------------------------------

SEGMENT: 6 2001 Condition
OBSERVED ESTIMATED T STATISTICS
VARIABLE MEAN CV MEAN CV RATIO 1 2 3
-------------------------------------------------------------------------
TOTAL P MG/M3 .0 .00 97.9 .12 .00 .00 .00 .00
TOTAL N MG/M3 .0 .00 1304.5 .19 .00 .00 .00 .00
C.NUTRIENT MG/M3 .0 .00 68.6 .13 .00 .00 .00 .00
CHL-A MG/M3 .0 .00 32.8 .31 .00 .00 .00 .00
-------------------------------------------------------------------------

SEGMENT: 7 AREA-WTD MEAN
OBSERVED ESTIMATED T STATISTICS
VARIABLE MEAN CV MEAN CV RATIO 1 2 3
-------------------------------------------------------------------------
TOTAL P MG/M3 .0 .00 59.6 .10 .00 .00 .00 .00
TOTAL N MG/M3 .0 .00 1304.5 .18 .00 .00 .00 .00
C.NUTRIENT MG/M3 .0 .00 47.9 .09 .00 .00 .00 .00
CHL-A MG/M3 .0 .00 21.3 .29 .00 .00 .00 .00
-------------------------------------------------------------------------
CASE: Roberson Creek Cove 2001

OBSERVED AND PREDICTED DIAGNOSTIC VARIABLES
RANKED AGAINST CE MODEL DEVELOPMENT DATA SET

SEGMENT: 1 TP -70.7%
----- VALUES ----- --- RANKS (%) ----
VARIABLE OBSERVED ESTIMATED OBSERVED ESTIMATED
--------------------------------------------------------
TOTAL P MG/M3 .00 37.34 .0 39.1
TOTAL N MG/M3 .00 1304.50 .0 66.0
C.NUTRIENT MG/M3 .00 34.81 .0 48.7
CHL-A MG/M3 .00 14.03 .0 69.9
(N - 150) / P .00 30.92 .0 81.0
CHL-A / TOTAL P .00 .38 .0 84.7
FREQ(CHL-a>10) % .00 59.36 .0 .0
FREQ(CHL-a>20) % .00 18.90 .0 .0
FREQ(CHL-a>30) % .00 6.23 .0 .0
FREQ(CHL-a>40) % .00 2.28 .0 .0
FREQ(CHL-a>50) % .00 .92 .0 .0
FREQ(CHL-a>60) % .00 .40 .0 .0
CARLSON TSI-P .00 56.35 .0 .0
CARLSON TSI-CHLA .00 56.51 .0 .0
--------------------------------------------------------

SEGMENT: 2 TP -49.6%
----- VALUES ----- --- RANKS (%) ----
VARIABLE OBSERVED ESTIMATED OBSERVED ESTIMATED
--------------------------------------------------------
TOTAL P MG/M3 .00 58.01 .0 58.4
TOTAL N MG/M3 .00 1304.48 .0 66.0
C.NUTRIENT MG/M3 .00 49.68 .0 66.0
CHL-A MG/M3 .00 21.89 .0 86.4
(N - 150) / P .00 19.90 .0 59.2
Roberson (Robeson) Creek TMDL

CHL-A / TOTAL P .00 .38 .0 84.9
FREQ(CHL-a>10) % .00 83.00 .0 .0
FREQ(CHL-a>20) % .00 43.48 .0 .0
FREQ(CHL-a>30) % .00 20.66 .0 .0
FREQ(CHL-a>40) % .00 9.99 .0 .0
FREQ(CHL-a>50) % .00 5.03 .0 .0
FREQ(CHL-a>60) % .00 2.64 .0 .0
CARLSON TSI-P .00 62.70 .0 .0
CARLSON TSI-CHLA .00 60.88 .0 .0
--------------------------------------------------------

SEGMENT: 3 TP -87.5%
----- VALUES ----- --- RANKS (%) ----
VARIABLE OBSERVED ESTIMATED OBSERVED ESTIMATED
--------------------------------------------------------
TOTAL P MG/M3 .00 18.13 .0 14.0
TOTAL N MG/M3 .00 1304.48 .0 66.0
C.NUTRIENT MG/M3 .00 17.82 .0 19.3
CHL-A MG/M3 .00 6.08 .0 28.6
(N - 150) / P .00 63.66 .0 97.4
CHL-A / TOTAL P .00 .34 .0 80.1
FREQ(CHL-a>10) % .00 13.28 .0 .0
FREQ(CHL-a>20) % .00 1.28 .0 .0
FREQ(CHL-a>30) % .00 .20 .0 .0
FREQ(CHL-a>40) % .00 .04 .0 .0
FREQ(CHL-a>50) % .00 .01 .0 .0
FREQ(CHL-a>60) % .00 .00 .0 .0
CARLSON TSI-P .00 45.94 .0 .0
CARLSON TSI-CHLA .00 48.30 .0 .0
--------------------------------------------------------

SEGMENT: 4 TP -25%
----- VALUES ----- --- RANKS (%) ----
VARIABLE OBSERVED ESTIMATED OBSERVED ESTIMATED
--------------------------------------------------------
TOTAL P MG/M3 .00 78.98 .0 71.1
TOTAL N MG/M3 .00 1304.48 .0 66.0
C.NUTRIENT MG/M3 .00 61.05 .0 74.9
CHL-A MG/M3 .00 28.33 .0 92.4
(N - 150) / P .00 14.62 .0 41.2
CHL-A / TOTAL P .00 .36 .0 82.9
FREQ(CHL-a>10) % .00 91.46 .0 .0
FREQ(CHL-a>20) % .00 59.93 .0 .0
FREQ(CHL-a>30) % .00 34.36 .0 .0
FREQ(CHL-a>40) % .00 19.30 .0 .0
FREQ(CHL-a>50) % .00 11.00 .0 .0
FREQ(CHL-a>60) % .00 6.42 .0 .0
CARLSON TSI-P .00 67.15 .0 .0
CARLSON TSI-CHLA .00 63.40 .0 .0
--------------------------------------------------------

SEGMENT: 5 TP -39%
----- VALUES ----- --- RANKS (%) ----
VARIABLE OBSERVED ESTIMATED OBSERVED ESTIMATED
--------------------------------------------------------
TOTAL P MG/M3 .00 67.37 .0 64.8
Roberson (Robeson) Creek TMDL

TOTAL N MG/M3 .00 1304.48 .0 66.0
C.NUTRIENT MG/M3 .00 55.19 .0 70.7
CHL-A MG/M3 .00 24.97 .0 89.8
(N - 150) / P .00 17.14 .0 50.5
CHL-A / TOTAL P .00 .37 .0 84.2
FREQ(CHL-a>10) % .00 87.82 .0 .0
FREQ(CHL-a>20) % .00 51.92 .0 .0
FREQ(CHL-a>30) % .00 27.22 .0 .0
FREQ(CHL-a>40) % .00 14.23 .0 .0
FREQ(CHL-a>50) % .00 7.63 .0 .0
FREQ(CHL-a>60) % .00 4.23 .0 .0
CARLSON TSI-P .00 64.86 .0 .0
CARLSON TSI-CHLA .00 62.16 .0 .0
--------------------------------------------------------

SEGMENT: 6 2001 Condition
----- VALUES ----- --- RANKS (%) ----
VARIABLE OBSERVED ESTIMATED OBSERVED ESTIMATED
--------------------------------------------------------
TOTAL P MG/M3 .00 97.93 .0 78.7
TOTAL N MG/M3 .00 1304.48 .0 66.0
C.NUTRIENT MG/M3 .00 68.63 .0 79.3
CHL-A MG/M3 .00 32.79 .0 94.8
(N - 150) / P .00 11.79 .0 29.5
CHL-A / TOTAL P .00 .33 .0 80.0
FREQ(CHL-a>10) % .00 94.58 .0 .0
FREQ(CHL-a>20) % .00 68.71 .0 .0
FREQ(CHL-a>30) % .00 43.38 .0 .0
FREQ(CHL-a>40) % .00 26.41 .0 .0
FREQ(CHL-a>50) % .00 16.09 .0 .0
FREQ(CHL-a>60) % .00 9.95 .0 .0
CARLSON TSI-P .00 70.26 .0 .0
CARLSON TSI-CHLA .00 64.84 .0 .0
--------------------------------------------------------

Roberson (Robeson) Creek TMDL

Appendix XI. Monthly average depth of irrigated water on the wastewater spray fields of Townsend Foods
Inc.

Month B1 B2 B3 B4 B5 R1 R2 R3 R4 R5
(in) (in) (in) (in) (in) (in) (in) (in) (in) (in)
Jan 0.83 0.00 0.00 0.00 0.00 0.80 0.67 0.86 0.82 0.82
Feb 0.59 0.59 0.56 0.32 0.55 0.62 0.64 0.73 0.62 0.49
Mar 0.50 0.49 0.47 0.59 0.56 0.52 0.77 0.77 0.53 0.90
Apr 1.36 1.29 1.35 1.14 1.12 1.50 1.60 1.84 1.59 1.76
May 1.02 1.10 1.22 1.07 1.11 0.79 0.76 0.85 0.78 0.73
Jun 1.47 1.36 1.44 1.64 1.72 1.24 1.31 1.41 1.19 1.50
Jul 1.43 1.40 1.45 1.16 1.05 1.47 1.70 1.75 1.87 1.68
Aug 1.08 1.10 1.02 1.16 1.30 1.19 1.18 1.14 1.18 1.36
Sep 1.65 1.64 2.05 1.39 1.55 1.62 1.72 1.66 1.59 1.85
Oct 0.90 0.98 0.79 0.99 0.95 0.82 0.66 0.94 0.86 0.85
Nov 0.78 0.89 0.87 0.94 0.93 1.00 1.09 1.22 0.90 1.08
Dec 0.51 0.62 0.42 0.43 0.61 0.72 0.42 0.72 0.75 0.67

Roberson (Robeson) Creek TMDL

Appendix XII. Daily average temperature and precipitation recorded in the Siler City Airport.

SilerCity SilerCity SilerCity SilerCity
Date-Time AirTempMax
C
AirTempMin
C
DailyPrecip in DailyPrecip mm
1/1/01 23:59 5.03 -7.80 0.00 0.00
1/2/01 23:59 3.42 -7.26 0.00 0.00
1/3/01 23:59 4.15 -13.62 0.00 0.00
1/4/01 23:59 6.92 -11.80 0.00 0.00
1/5/01 23:59 10.98 -9.02 0.00 0.00
1/6/01 23:59 10.03 -5.64 0.00 0.00
1/7/01 23:59 13.61 -4.22 0.00 0.00
1/8/01 23:59 7.54 0.98 0.11 2.79
1/9/01 23:59 4.22 -3.54 0.00 0.00
1/10/01 23:59 12.73 -6.38 0.00 0.00
1/11/01 23:59 16.64 -5.84 0.00 0.00
1/12/01 23:59 8.55 1.72 0.19 4.83
1/13/01 23:59 12.93 0.11 0.00 0.00
1/14/01 23:59 9.63 4.83 0.00 0.00
1/15/01 23:59 17.79 3.01 0.04 1.02
1/16/01 23:59 14.56 0.85 0.00 0.00
1/17/01 23:59 9.76 -2.20 0.00 0.00
1/18/01 23:59 6.72 4.22 0.06 1.52
1/19/01 23:59 21.50 5.64 0.31 7.87
1/20/01 23:59 16.30 -0.30 0.31 7.87
1/21/01 23:59 6.65 -6.18 0.00 0.00
1/22/01 23:59 8.41 -6.99 0.00 0.00
1/23/01 23:59 10.64 -4.83 0.00 0.00
1/24/01 23:59 13.95 -3.41 0.00 0.00
1/25/01 23:59 5.98 -2.66 0.00 0.00
1/26/01 23:59 8.61 -8.95 0.00 0.00
1/27/01 23:59 15.16 -0.98 0.00 0.00
1/28/01 23:59 13.13 -6.25 0.00 0.00
1/29/01 23:59 16.71 -2.66 0.00 0.00
1/30/01 23:59 18.67 10.84 0.30 7.62
1/31/01 23:59 19.54 7.40 0.00 0.00
2/1/01 23:59 10.37 1.25 0.00 0.00
2/2/01 23:59 11.99 0.45 0.00 0.00
2/3/01 23:59 8.81 -4.69 0.00 0.00
2/4/01 23:59 6.86 -2.32 0.04 1.02
2/5/01 23:59 14.35 -1.78 0.01 0.25
2/6/01 23:59 14.62 -5.43 0.00 0.00
2/7/01 23:59 20.88 -3.07 0.00 0.00
2/8/01 23:59 20.62 -0.37 0.00 0.00
2/9/01 23:59 21.70 6.80 0.00 0.00
2/10/01 23:59 17.79 2.34 0.10 2.54
2/11/01 23:59 10.03 -0.70 0.00 0.00
2/12/01 23:59 4.36 -1.11 0.14 3.56
2/13/01 23:59 13.87 0.31 0.14 3.56
Roberson (Robeson) Creek TMDL

2/14/01 23:59 15.29 8.75 0.07 1.78
2/15/01 23:59 21.16 15.08 0.00 0.00
2/16/01 23:59 24.47 11.23 0.34 8.64
2/17/01 23:59 11.78 -0.10 0.56 14.22
2/18/01 23:59 6.12 -4.96 0.00 0.00
2/19/01 23:59 12.73 -5.30 0.00 0.00
2/20/01 23:59 20.41 0.72 0.00 0.00
2/21/01 23:59 17.52 5.03 0.00 0.00
2/22/01 23:59 7.74 -3.95 0.00 0.00
2/23/01 23:59 11.38 -6.98 0.25 6.35
2/24/01 23:59 15.57 -2.19 0.00 0.00
2/25/01 23:59 19.61 8.68 0.17 4.32
2/26/01 23:59 20.82 6.25 0.00 0.00
2/27/01 23:59 18.20 -0.50 0.00 0.00
2/28/01 23:59 13.67 6.04 0.00 0.00
3/1/01 23:59 16.10 0.64 0.00 0.00
3/2/01 23:59 22.23 2.14 0.00 0.00
3/3/01 23:59 12.06 8.14 0.42 10.67
3/4/01 23:59 9.29 7.74 0.62 15.75
3/5/01 23:59 11.79 0.71 0.11 2.79
3/6/01 23:59 4.49 -2.66 0.00 0.00
3/7/01 23:59 8.82 -1.85 0.00 0.00
3/8/01 23:59 14.48 -5.70 0.00 0.00
3/9/01 23:59 14.68 -0.30 0.00 0.00
3/10/01 23:59 13.00 -6.85 0.00 0.00
3/11/01 23:59 18.87 -2.05 0.00 0.00
3/12/01 23:59 19.61 2.54 0.10 2.54
3/13/01 23:59 23.31 13.14 0.00 0.00
3/14/01 23:59 20.88 5.72 0.00 0.00
3/15/01 23:59 12.01 7.19 0.46 11.68
3/16/01 23:59 10.64 5.70 0.00 0.00
3/17/01 23:59 17.65 3.61 0.01 0.25
3/18/01 23:59 13.67 0.44 0.00 0.00
3/19/01 23:59 13.74 -1.37 0.00 0.00
3/20/01 23:59 7.60 3.62 1.01 25.65
3/21/01 23:59 10.17 6.79 0.18 4.57
3/22/01 23:59 17.59 4.09 0.01 0.25
3/23/01 23:59 19.53 -2.33 0.00 0.00
3/24/01 23:59 23.38 -0.51 0.00 0.00
3/25/01 23:59 13.53 3.41 0.00 0.00
3/26/01 23:59 9.82 -0.57 0.00 0.00
3/27/01 23:59 9.28 -4.35 0.00 0.00
3/28/01 23:59 13.60 -6.25 0.00 0.00
3/29/01 23:59 8.69 3.34 1.80 45.72
3/30/01 23:59 21.02 5.84 0.21 5.33
3/31/01 23:59 20.62 5.78 0.49 12.45
4/1/01 23:59 14.08 4.30 0.17 4.32
4/2/01 23:59 17.58 -0.44 0.00 0.00
4/3/01 23:59 15.77 7.33 0.11 2.79
Roberson (Robeson) Creek TMDL

4/4/01 23:59 13.34 3.22 0.00 0.00
4/5/01 23:59 19.46 0.44 0.00 0.00
4/6/01 23:59 26.00 6.92 0.00 0.00
4/7/01 23:59 30.99 14.89 0.00 0.00
4/8/01 23:59 32.07 18.06 0.00 0.00
4/9/01 23:59 32.95 14.75 0.00 0.00
4/10/01 23:59 33.01 13.88 0.00 0.00
4/11/01 23:59 27.61 16.17 0.00 0.00
4/12/01 23:59 30.24 17.72 0.00 0.00
4/13/01 23:59 25.80 12.60 0.02 0.51
4/14/01 23:59 25.94 8.28 0.00 0.00
4/15/01 23:59 23.65 9.16 0.01 0.25
4/16/01 23:59 20.68 6.92 0.00 0.00
4/17/01 23:59 12.35 1.53 0.04 1.02
4/18/01 23:59 12.73 -2.59 0.00 0.00
4/19/01 23:59 18.32 -3.47 0.00 0.00
4/20/01 23:59 22.37 1.73 0.00 0.00
4/21/01 23:59 26.07 11.39 0.00 0.00
4/22/01 23:59 27.75 10.37 0.00 0.00
4/23/01 23:59 28.16 11.38 0.00 0.00
4/24/01 23:59 29.50 13.88 0.00 0.00
4/25/01 23:59 14.21 2.34 0.63 16.00
4/26/01 23:59 19.54 1.53 0.01 0.25
4/27/01 23:59 26.00 0.92 0.00 0.00
4/28/01 23:59 27.62 7.07 0.00 0.00
4/29/01 23:59 20.00 9.97 0.00 0.00
4/30/01 23:59 25.66 3.62 0.00 0.00
5/1/01 23:59 27.14 9.77 0.00 0.00
5/2/01 23:59 27.82 10.51 0.00 0.00
5/3/01 23:59 29.09 9.70 0.00 0.00
5/4/01 23:59 30.38 9.50 0.00 0.00
5/5/01 23:59 31.60 11.99 0.00 0.00
5/6/01 23:59 21.35 12.59 0.00 0.00
5/7/01 23:59 22.43 8.48 0.00 0.00
5/8/01 23:59 24.60 7.54 0.00 0.00
5/9/01 23:59 27.08 10.24 0.00 0.00
5/10/01 23:59 27.88 10.64 0.00 0.00
5/11/01 23:59 30.85 12.33 0.00 0.00
5/12/01 23:59 30.17 13.61 0.06 1.52
5/13/01 23:59 23.65 7.53 0.01 0.25
5/14/01 23:59 24.59 3.70 0.00 0.00
5/15/01 23:59 24.05 8.41 0.14 3.56
5/16/01 23:59 18.60 12.19 0.24 6.10
5/17/01 23:59 14.75 11.78 0.05 1.27
5/18/01 23:59 30.38 13.47 0.00 0.00
5/19/01 23:59 33.14 14.35 0.01 0.25
5/20/01 23:59 27.87 17.25 0.00 0.00
5/21/01 23:59 27.42 18.60 0.00 0.00
5/22/01 23:59 30.45 17.11 0.32 8.13
Roberson (Robeson) Creek TMDL

5/23/01 23:59 25.93 9.97 0.01 0.25
5/24/01 23:59 29.51 7.13 0.00 0.00
5/25/01 23:59 27.83 16.65 0.02 0.51
5/26/01 23:59 25.20 11.38 0.32 8.13
5/27/01 23:59 28.56 8.01 0.00 0.00
5/28/01 23:59 21.36 11.32 0.30 7.62
5/29/01 23:59 26.54 12.53 0.08 2.03
5/30/01 23:59 28.36 10.04 0.00 0.00
-99.00 -99.00 -99.00 -99.00
-99.00 -99.00 -99.00 -99.00
-99.00 -99.00 -99.00 -99.00
-99.00 -99.00 -99.00 -99.00
-99.00 -99.00 -99.00 -99.00
-99.00 -99.00 -99.00 -99.00
-99.00 -99.00 -99.00 -99.00
-99.00 -99.00 -99.00 -99.00
-99.00 -99.00 -99.00 -99.00
-99.00 -99.00 -99.00 -99.00
-99.00 -99.00 -99.00 -99.00
-99.00 -99.00 -99.00 -99.00
-99.00 -99.00 -99.00 -99.00
-99.00 -99.00 -99.00 -99.00
6/14/01 23:59 29.11 20.75 0.37 9.40
6/15/01 23:59 31.26 19.61 0.00 0.00
6/16/01 23:59 32.68 17.79 0.06 1.52
6/17/01 23:59 32.74 17.26 0.00 0.00
6/18/01 23:59 31.12 13.61 0.00 0.00
6/19/01 23:59 31.05 16.85 0.00 0.00
6/20/01 23:59 32.00 15.84 0.00 0.00
6/21/01 23:59 32.81 18.74 0.00 0.00
6/22/01 23:59 32.48 18.40 2.07 52.58
6/23/01 23:59 28.22 18.81 0.08 2.03
6/24/01 23:59 27.76 18.47 0.00 0.00
6/25/01 23:59 27.29 18.46 0.18 4.57
6/26/01 23:59 30.72 19.34 0.00 0.00
6/27/01 23:59 32.61 17.73 0.00 0.00
6/28/01 23:59 32.81 18.20 0.00 0.00
6/29/01 23:59 32.48 17.72 0.00 0.00
6/30/01 23:59 32.27 18.88 0.00 0.00
7/1/01 23:59 31.46 20.15 0.10 2.54
7/2/01 23:59 28.82 18.47 0.02 0.51
7/3/01 23:59 28.30 18.54 0.00 0.00
7/4/01 23:59 31.60 19.61 2.46 62.48
7/5/01 23:59 30.31 19.47 0.00 0.00
7/6/01 23:59 28.90 15.97 0.00 0.00
7/7/01 23:59 29.36 14.35 0.00 0.00
7/8/01 23:59 27.36 19.21 0.30 7.62
7/9/01 23:59 32.00 19.47 0.00 0.00
7/10/01 23:59 33.68 19.61 0.00 0.00
Roberson (Robeson) Creek TMDL

7/11/01 23:59 33.48 19.68 0.60 15.24
7/12/01 23:59 30.85 18.20 0.00 0.00
7/13/01 23:59 25.93 15.16 0.00 0.00
7/14/01 23:59 29.10 12.26 0.00 0.00
7/15/01 23:59 30.51 11.93 0.00 0.00
7/16/01 23:59 31.66 13.27 0.00 0.00
7/17/01 23:59 31.32 16.38 0.00 0.00
7/18/01 23:59 31.26 19.35 0.11 2.79
7/19/01 23:59 29.23 20.08 0.01 0.25
7/20/01 23:59 28.10 16.04 0.00 0.00
7/21/01 23:59 28.96 13.75 0.00 0.00
7/22/01 23:59 30.11 13.28 0.00 0.00
7/23/01 23:59 31.66 17.59 0.00 0.00
7/24/01 23:59 29.65 22.84 0.63 16.00
7/25/01 23:59 31.05 20.76 0.12 3.05
7/26/01 23:59 29.52 20.69 0.25 6.35
7/27/01 23:59 25.01 19.47 0.37 9.40
7/28/01 23:59 23.04 17.99 0.00 0.00
7/29/01 23:59 26.15 17.93 0.03 0.76
7/30/01 23:59 25.94 16.58 0.10 2.54
7/31/01 23:59 29.03 14.89 0.00 0.00
8/1/01 23:59 26.54 15.16 0.00 0.00
8/2/01 23:59 29.10 12.47 0.00 0.00
8/3/01 23:59 31.19 13.08 0.00 0.00
8/4/01 23:59 31.19 18.94 0.00 0.00
8/5/01 23:59 32.14 15.97 0.00 0.00
8/6/01 23:59 33.29 16.85 0.00 0.00
8/7/01 23:59 35.77 21.23 0.00 0.00
8/8/01 23:59 36.04 22.04 0.00 0.00
8/9/01 23:59 37.25 19.75 0.20 5.08
8/10/01 23:59 35.44 20.76 0.03 0.76
8/11/01 23:59 34.57 20.83 0.73 18.54
8/12/01 23:59 33.08 20.83 0.00 0.00
8/13/01 23:59 29.52 22.18 0.04 1.02
8/14/01 23:59 30.92 19.28 0.00 0.00
8/15/01 23:59 31.60 18.27 0.00 0.00
8/16/01 23:59 32.00 17.46 0.00 0.00
8/17/01 23:59 32.95 23.99 0.02 0.51
8/18/01 23:59 29.32 20.29 1.09 27.69
8/19/01 23:59 30.24 21.36 0.02 0.51
8/20/01 23:59 31.48 20.42 0.00 0.00
8/21/01 23:59 29.85 15.17 0.00 0.00
8/22/01 23:59 31.05 13.41 0.00 0.00
8/23/01 23:59 32.34 14.29 0.47 11.94
8/24/01 23:59 28.37 18.13 0.88 22.35
8/25/01 23:59 29.85 15.44 0.00 0.00
8/26/01 23:59 30.38 14.29 0.00 0.00
8/27/01 23:59 33.35 18.20 0.34 8.64
8/28/01 23:59 31.66 18.27 0.01 0.25
Roberson (Robeson) Creek TMDL

8/29/01 23:59 32.75 21.50 0.00 0.00
8/30/01 23:59 29.33 20.02 0.53 13.46
8/31/01 23:59 30.05 21.24 0.12 3.05
9/1/01 23:59 25.14 20.15 0.10 2.54
9/2/01 23:59 27.56 18.81 0.00 0.00
9/3/01 23:59 23.59 19.35 0.00 0.00
9/4/01 23:59 25.14 17.67 0.19 4.83
9/5/01 23:59 30.12 16.31 0.00 0.00
9/6/01 23:59 29.11 15.84 0.00 0.00
9/7/01 23:59 28.98 13.41 0.00 0.00
9/8/01 23:59 29.71 12.94 0.00 0.00
9/9/01 23:59 29.99 14.76 0.00 0.00
9/10/01 23:59 31.05 21.23 0.01 0.25
9/11/01 23:59 28.03 13.62 0.00 0.00
9/12/01 23:59 28.71 10.79 0.00 0.00
9/13/01 23:59 27.63 10.72 0.00 0.00
9/14/01 23:59 26.36 10.85 0.00 0.00
9/15/01 23:59 22.11 9.91 0.00 0.00
9/16/01 23:59 24.33 7.61 0.00 0.00
9/17/01 23:59 26.56 4.51 0.00 0.00
9/18/01 23:59 28.78 6.94 0.00 0.00
9/19/01 23:59 28.78 9.50 0.00 0.00
9/20/01 23:59 27.44 16.78 0.39 9.91
9/21/01 23:59 29.25 14.90 0.01 0.25
9/22/01 23:59 30.80 13.28 0.00 0.00
9/23/01 23:59 31.60 16.45 0.00 0.00
9/24/01 23:59 23.73 18.40 1.07 27.18
9/25/01 23:59 20.96 6.73 0.01 0.25
9/26/01 23:59 20.96 2.68 0.00 0.00
9/27/01 23:59 25.08 4.31 0.00 0.00
9/28/01 23:59 21.64 6.87 0.00 0.00
9/29/01 23:59 20.69 5.04 0.00 0.00
9/30/01 23:59 19.61 3.49 0.00 0.00
10/1/01 23:59 23.46 0.25 0.00 0.00
10/2/01 23:59 26.95 4.17 0.00 0.00
10/3/01 23:59 28.98 7.07 0.00 0.00
10/4/01 23:59 28.98 8.08 0.00 0.00
10/5/01 23:59 28.57 9.57 0.00 0.00
10/6/01 23:59 20.90 4.03 0.33 8.38
10/7/01 23:59 18.67 -0.22 0.00 0.00
10/8/01 23:59 17.05 -0.29 0.00 0.00
10/9/01 23:59 18.40 -1.57 0.00 0.00
10/10/01 23:59 24.60 2.41 0.00 0.00
10/11/01 23:59 26.08 7.54 0.00 0.00
10/12/01 23:59 25.21 8.48 0.00 0.00
10/13/01 23:59 26.81 8.82 0.00 0.00
10/14/01 23:59 24.20 14.29 0.84 21.34
10/15/01 23:59 22.91 6.13 0.00 0.00
10/16/01 23:59 24.60 3.90 0.00 0.00
Roberson (Robeson) Creek TMDL

10/17/01 23:59 17.73 -0.36 0.00 0.00
10/18/01 23:59 17.86 -1.91 0.00 0.00
10/19/01 23:59 23.18 -1.84 0.00 0.00
10/20/01 23:59 25.67 4.57 0.00 0.00
10/21/01 23:59 27.90 4.78 0.00 0.00
10/22/01 23:59 29.45 11.18 0.00 0.00
10/23/01 23:59 29.66 10.18 0.00 0.00
10/24/01 23:59 30.46 12.74 0.00 0.00
10/25/01 23:59 25.68 6.73 0.12 3.05
10/26/01 23:59 18.61 1.53 0.00 0.00
10/27/01 23:59 10.31 -3.13 0.00 0.00
10/28/01 23:59 13.20 -2.93 0.00 0.00
10/29/01 23:59 18.20 -5.09 0.00 0.00
10/30/01 23:59 23.59 -2.66 0.00 0.00
10/31/01 23:59 22.23 0.64 0.00 0.00
11/1/01 23:59 25.28 2.75 0.00 0.00
11/2/01 23:59 26.50 13.01 0.00 0.00
11/3/01 23:59 28.64 10.71 0.00 0.00
11/4/01 23:59 21.76 1.94 0.00 0.00
11/5/01 23:59 18.81 0.12 0.00 0.00
-99.00 -99.00 -99.00 -99.00
11/7/01 23:59 24.67 -2.72 0.00 0.00
11/8/01 23:59 25.96 -1.30 0.00 0.00
11/9/01 23:59 20.69 -1.10 0.00 0.00
-99.00 -99.00 -99.00 -99.00
-99.00 -99.00 -99.00 -99.00
11/12/01 23:59 15.63 -2.66 0.00 0.00
11/13/01 23:59 16.51 -4.69 0.00 0.00
11/14/01 23:59 20.43 -1.44 0.00 0.00
11/15/01 23:59 21.71 1.13 0.00 0.00
11/16/01 23:59 24.74 -0.22 0.00 0.00
11/17/01 23:59 22.43 4.17 0.00 0.00
11/18/01 23:59 19.47 0.92 0.00 0.00
11/19/01 23:59 21.78 3.16 0.00 0.00
11/20/01 23:59 15.03 2.15 0.00 0.00
11/21/01 23:59 12.94 -4.82 0.00 0.00
11/22/01 23:59 18.07 -5.90 0.00 0.00
11/23/01 23:59 19.62 -2.93 0.01 0.25
11/24/01 23:59 20.83 10.64 0.35 8.89
11/25/01 23:59 22.86 17.06 0.01 0.25
11/26/01 23:59 24.06 9.30 0.00 0.00
11/27/01 23:59 25.62 8.35 0.00 0.00
11/28/01 23:59 26.69 10.38 0.00 0.00
11/29/01 23:59 24.33 11.40 0.01 0.25
11/30/01 23:59 20.56 14.35 0.00 0.00
12/1/01 23:59 22.31 4.98 0.01 0.25
12/2/01 23:59 17.53 3.16 0.00 0.00
12/3/01 23:59 17.19 -1.98 0.00 0.00
12/4/01 23:59 23.33 -3.40 0.00 0.00
Roberson (Robeson) Creek TMDL

12/5/01 23:59 25.48 -1.03 0.00 0.00
12/6/01 23:59 24.33 4.24 0.00 0.00
12/7/01 23:59 24.94 8.62 0.00 0.00
12/8/01 23:59 23.72 9.09 0.00 0.00
12/9/01 23:59 16.38 7.06 0.00 0.00
12/10/01 23:59 7.35 5.18 1.05 26.67
12/11/01 23:59 9.43 4.77 0.39 9.91
12/12/01 23:59 11.12 8.62 0.01 0.25
12/13/01 23:59 14.15 9.91 0.04 1.02
12/14/01 23:59 20.90 12.94 0.01 0.25
12/15/01 23:59 16.78 0.66 0.00 0.00
12/16/01 23:59 14.90 -1.64 0.00 0.00
12/17/01 23:59 20.83 2.14 0.43 10.92
12/18/01 23:59 17.46 -0.90 0.01 0.25
12/19/01 23:59 17.67 -2.99 0.00 0.00
12/20/01 23:59 10.38 -4.28 0.00 0.00
12/21/01 23:59 11.99 -6.10 0.00 0.00
12/22/01 23:59 11.52 -7.66 0.00 0.00
12/23/01 23:59 15.98 -3.60 0.03 0.76
12/24/01 23:59 14.69 -3.06 0.10 2.54
12/25/01 23:59 8.14 -6.92 0.00 0.00
12/26/01 23:59 8.28 -5.90 0.00 0.00
12/27/01 23:59 7.20 -8.74 0.00 0.00
12/28/01 23:59 13.08 -6.85 0.00 0.00
12/29/01 23:59 16.25 -1.24 0.00 0.00
12/30/01 23:59 6.93 -5.22 0.00 0.00
12/31/01 23:59 5.11 -6.44 0.00 0.00

Roberson (Robeson) Creek TMDL

Appendix XIII. Daily average flow and concentration of total Phosphorus discharged from the Pittsboro
WWTP to Roberson Creek during 2001.

Date Flow P Date Flow P Date Flow P
mgd mg/l mgd mg/l mgd mg/l
2001/01/01 0.239 1.4 2001/05/01 0.496 3.57 2001/09/01 0.6
2001/01/02 0.247 2001/05/02 0.335 2001/09/02 0.482
2001/01/03 0.223 2001/05/03 0.281 2001/09/03 0.231 0.59
2001/01/04 0.279 2001/05/04 0.277 2001/09/04 0.223
2001/01/05 0.227 1.4 2001/05/05 0.268 2001/09/05 0.257 0.59
2001/01/06 0.218 2001/05/06 0.294 2001/09/06 0.268
2001/01/07 0.244 2001/05/07 0.473 2001/09/07 0.271
2001/01/08 0.259 2001/05/08 0.469 2001/09/08 0.224
2001/01/09 0.249 2001/05/09 0.469 2.71 2001/09/09 0.232
2001/01/10 0.257 2.05 2001/05/10 0.436 2001/09/10 0.265 0.8
2001/01/11 0.254 2001/05/11 0.447 2001/09/11 0.213
2001/01/12 0.257 2001/05/12 0.448 2001/09/12 0.229
2001/01/13 0.251 2001/05/13 0.436 2001/09/13 0.194
2001/01/14 0.254 2001/05/14 0.47 2001/09/14 0.267
2001/01/15 0.246 2.54 2001/05/15 0.6 2001/09/15 0.144
2001/01/16 0.254 2001/05/16 0.609 2.96 2001/09/16 0.137
2001/01/17 0.261 2001/05/17 0.526 2001/09/17 0.145
2001/01/18 0.28 2.54 2001/05/18 0.517 2001/09/18 0.245
2001/01/19 0.41 2001/05/19 0.49 2001/09/19 0.214 1.28
2001/01/20 0.375 2001/05/20 0.503 2001/09/20 0.215
2001/01/21 0.282 2001/05/21 0.535 2001/09/21 0.209
2001/01/22 0.306 1.73 2001/05/22 0.563 2001/09/22 0.133
2001/01/23 0.293 2001/05/23 0.467 3.31 2001/09/23 0.168
2001/01/24 0.281 2001/05/24 0.54 2001/09/24 0.389 0.89
2001/01/25 0.256 2001/05/25 0.51 2001/09/25 0.23
2001/01/26 0.239 2001/05/26 0.473 2001/09/26 0.161
2001/01/27 0.241 2001/05/27 0.452 2001/09/27 0.16
2001/01/28 0.244 2001/05/28 0.527 1.06 2001/09/28 0.146
2001/01/29 0.29 2001/05/29 0.529 2001/09/29 0.158
2001/01/30 0.313 2001/05/30 0.496 2001/09/30 0.172
2001/01/31 0.261 1.43 2001/05/31 0.486 1.06 2001/10/01 0.216
2001/02/01 0.269 2001/06/01 0.949 2001/10/02 0.156 1.42
2001/02/02 0.258 2001/06/02 0.713 2001/10/03 0.22
2001/02/03 0.229 2001/06/03 0.399 2001/10/04 0.144
2001/02/04 0.288 2001/06/04 0.386 2001/10/05 0.182
2001/02/05 0.271 2001/06/05 0.35 2001/10/06 0.166
2001/02/06 0.284 2001/06/06 0.472 2001/10/07 0.206
2001/02/07 0.255 2.2 2001/06/07 0.316 0.72 2001/10/08 0.171
2001/02/08 0.255 2001/06/08 0.327 0.69 2001/10/09 0.164 1.12
2001/02/09 0.255 2001/06/09 0.289 2001/10/10 0.186
2001/02/10 0.249 2001/06/10 0.299 2001/10/11 0.128
2001/02/11 0.276 2001/06/11 0.293 2001/10/12 0.308
Roberson (Robeson) Creek TMDL

2001/02/12 0.432 2001/06/12 0.331 0.58 2001/10/13 0.227
2001/02/13 0.371 2001/06/13 0.55 0.8 2001/10/14 0.191
2001/02/14 0.34 2001/06/14 0.569 2001/10/15 0.18
2001/02/15 0.38 1.99 2001/06/15 0.387 2001/10/16 0.195
2001/02/16 0.674 2001/06/16 0.378 2001/10/17 0.199 0.7
2001/02/17 0.571 2001/06/17 0.34 2001/10/18 0.212
2001/02/18 0.44 2001/06/18 0.339 2001/10/19 0.194
2001/02/19 0.458 2001/06/19 0.273 2001/10/20 0.171
2001/02/20 0.425 2001/06/20 0.357 1.79 2001/10/21 0.156
2001/02/21 0.391 2001/06/21 0.323 2001/10/22 0.171
2001/02/22 0.446 1.97 2001/06/22 0.87 2001/10/23 0.221
2001/02/23 0.443 2001/06/23 0.485 2001/10/24 0.243 1.93
2001/02/24 0.406 2001/06/24 0.572 2001/10/25 0.234
2001/02/25 0.439 2001/06/25 0.557 2001/10/26 0.216
2001/02/26 0.427 2001/06/26 0.473 2001/10/27 0.16
2001/02/27 0.413 2001/06/27 0.425 2001/10/28 0.12
2001/02/28 0.423 1.63 2001/06/28 0.402 1.19 2001/10/29 0.185
2001/03/01 0.401 2001/06/29 0.388 2001/10/30 0.191 1.12
2001/03/02 0.417 2001/06/30 0.364 2001/10/31 0.214
2001/03/03 0.972 2001/07/01 0.398 2001/11/01 0.2
2001/03/04 0.718 2001/07/02 0.354 2001/11/02 0.2
2001/03/05 0.619 2001/07/03 0.33 2001/11/03 0.188
2001/03/06 0.538 1.34 2001/07/04 1.366 2001/11/04 0.16
2001/03/07 0.479 2001/07/05 0.7 2001/11/05 0.171
2001/03/08 0.452 2001/07/06 0.494 0.84 2001/11/06 0.387 1.52
2001/03/09 0.438 2001/07/07 0.429 2001/11/07 0.182
2001/03/10 0.415 2001/07/08 0.481 2001/11/08 0.189
2001/03/11 0.416 2001/07/09 0.579 0.81 2001/11/09 0.192
2001/03/12 0.451 1.62 2001/07/10 0.462 2001/11/10 0.16
2001/03/13 0.433 2001/07/11 0.409 2001/11/11 0.167
2001/03/14 0.45 2001/07/12 0.389 2001/11/12 0.187
2001/03/15 0.587 2001/07/13 0.35 2001/11/13 0.187 1.01
2001/03/16 0.497 2001/07/14 0.327 2001/11/14 0.256
2001/03/17 0.443 2001/07/15 0.322 2001/11/15 0.251
2001/03/18 0.443 2001/07/16 0.311 5.77 2001/11/16 0.233
2001/03/19 0.332 2001/07/17 0.313 2001/11/17 0.232
2001/03/20 1.136 2001/07/18 0.304 2001/11/18 0.249
2001/03/21 0.92 2001/07/19 0.303 2001/11/19 0.268
2001/03/22 0.672 2001/07/20 0.273 2001/11/20 0.262 0.87
2001/03/23 0.593 2.33 2001/07/21 0.254 2001/11/21 0.248
2001/03/24 0.517 2001/07/22 0.267 2001/11/22 0.212
2001/03/25 0.519 2001/07/23 0.319 2.04 2001/11/23 0.241
2001/03/26 0.499 2.74 2001/07/24 0.383 2001/11/24 0.234
2001/03/27 0.465 2001/07/25 0.485 2001/11/25 0.251
2001/03/28 0.571 2001/07/26 0.32 2001/11/26 0.267
2001/03/29 1.82 2001/07/27 0.502 2001/11/27 0.267 0.69
2001/03/30 1.062 2001/07/28 0.34 2001/11/28 0.256
2001/03/31 1.084 2001/07/29 0.327 2001/11/29 0.266
2001/04/01 1.312 2001/07/30 0.325 1.76 2001/11/30 0.255
Roberson (Robeson) Creek TMDL

2001/04/02 0.834 2001/07/31 0.316 2001/12/01 0.242
2001/04/03 0.713 2001/08/01 0.3 2001/12/02 0.254
2001/04/04 0.622 2001/08/02 0.297 2001/12/03 0.297
2001/04/05 0.628 2001/08/03 0.291 2001/12/04 0.3 1.09
2001/04/06 0.629 2.18 2001/08/04 0.271 2001/12/05 0.313
2001/04/07 0.617 2001/08/05 0.281 2001/12/06 0.311
2001/04/08 0.623 2001/08/06 0.302 2001/12/07 0.289
2001/04/09 0.609 2001/08/07 0.298 2.41 2001/12/08 0.287
2001/04/10 0.586 2001/08/08 0.296 2001/12/09 0.276
2001/04/11 0.599 3.4 2001/08/09 0.244 2001/12/10 0.29
2001/04/12 0.6 2001/08/10 0.245 2001/12/11 0.359
2001/04/13 0.5 2001/08/11 0.926 2001/12/12 0.385
2001/04/14 0.488 2001/08/12 1.235 2001/12/13 0.354
2001/04/15 0.458 2001/08/13 0.588 2001/12/14 0.352
2001/04/16 0.454 3.71 2001/08/14 0.327 2001/12/15 0.356
2001/04/17 0.314 2001/08/15 0.255 2001/12/16 0.319
2001/04/18 0.471 2001/08/16 0.254 1.24 2001/12/17 0.327
2001/04/19 0.473 2001/08/17 0.23 2001/12/18 0.405 1.63
2001/04/20 0.461 3.71 2001/08/18 0.222 2001/12/19 0.399
2001/04/21 0.477 2001/08/19 0.233 2001/12/20 0.348
2001/04/22 0.494 2001/08/20 0.215 2001/12/21 0.352
2001/04/23 0.509 2001/08/21 0.199 1.73 2001/12/22 0.34
2001/04/24 0.547 2001/08/22 0.2 2001/12/23 0.319
2001/04/25 0.514 2001/08/23 0.206 2001/12/24 0.477 1.63
2001/04/26 0.493 2.77 2001/08/24 0.21 2001/12/25 0.312 1.63
2001/04/27 0.47 2001/08/25 0.209 2001/12/26 0.341 2.47
2001/04/28 0.49 2001/08/26 0.214 2001/12/27 0.36 2.47
2001/04/29 0.4 2001/08/27 0.238 2001/12/28 0.345
2001/04/30 0.449 2001/08/28 0.278 1.08 2001/12/29 0.323
2001/08/29 0.255 2001/12/30 0.342
2001/08/30 0.232 2001/12/31 0.317
2001/08/31 0.901