RichlandMuddyCreeksFecalTMDLFinal

Total Maximum Daily Loads for
Fecal Coliform for
Richland Creek and Muddy Creek,
North Carolina

Final Report
February 2004
(Approved May 17, 2004)

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]

With support from:
TetraTech, Inc.
Cape Fear Bldg., Suite 105
3200 Chapel Hill-Nelson Hwy.
Research Triangle Park, NC 27709
NC DWQ Contract Number EW030318; Project Number 1-5
Cape Fear River Basin

Richland Creek and Muddy Creek TMDLs March 2004

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Table of Contents
List of Tables ii
List of Figures iii
1 Introduction..................................................................................................................1
1.1 Problem Definition........................................................................................................................ 1
1.1.1 TMDL Components.............................................................................................................. 2
1.1.2 Richland Creek and Muddy Creek Fecal Coliform Impairments ......................................... 2
1.2 Watershed Description.................................................................................................................. 3
1.2.1 Landuse Distribution in the Richland Creek and Muddy Creek Watersheds ...................... 3
1.3 Water Quality Monitoring............................................................................................................. 4
1.3.1 NCDENR Monitoring........................................................................................................... 4
1.3.2 UCFRBA Fecal Monitoring Data......................................................................................... 5
1.3.3 Summary of Fecal Coliform Trends..................................................................................... 6
2 Source Assessment.......................................................................................................9
2.1 General Sources of Fecal Coliform............................................................................................... 9
2.1.1 Nonpoint Source Fecal Coliform Contributions................................................................... 9
2.1.2 Point Source Fecal Coliform Contributions........................................................................ 14
3 Technical Approach...................................................................................................17
3.1 TMDL Endpoints ........................................................................................................................ 17
3.2 Flow-Duration Curves for Fecal Coliform.................................................................................. 17
3.3 Determination of Existing Fecal Coliform Load and Assimilative Capacity.............................. 21
4 TMDL Development..................................................................................................25
4.1 TMDL Definition........................................................................................................................ 25
4.2 TMDL Endpoints ........................................................................................................................ 25
4.3 Critical Conditions ...................................................................................................................... 25
4.4 Seasonal Variations..................................................................................................................... 25
4.5 Margin of Safety (MOS) ............................................................................................................. 25
4.6 TMDL Curves............................................................................................................................. 26
4.7 TMDL Summary......................................................................................................................... 29
5 Report Summary........................................................................................................32
6 TMDL Implementation Plan......................................................................................34
7 Stream Monitoring.....................................................................................................36
8 Future Efforts.............................................................................................................38
9 Public Participation....................................................................................................40
10 Further Information.................................................................................................... 42
11 References 44
12 Appendices 46
Appendix A Water Quality Sampling Data ........................................................................................ 48
Appendix B Load Reduction Calculations ......................................................................................... 54
Appendix C Affidavits of Publication for Public Notice.................................................................... 60
Richland Creek and Muddy Creek TMDLs March 2004

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List of Tables
Table 1. Watershed NLCD Landuse Acreage and Percent Composition...................................3
Table 2. Summary of NCDENR Water Quality Monitoring for Fecal Coliform Impairment....5
Table 3. Summary of UCFRBA Fecal Coliform Monitoring Data (4/27/00 through 6/5/03)....6
Table 4. NPDES Facilities Discharging Fecal Coliform ..........................................................15
Table 5. Flow Statistics for USGS Gage 02099000..................................................................18
Table 6. Relative Proportion of Flow at USGS Gage 02099000 (East Fork Deep River) for
Each Monitoring Station Drainage Area................................................................................18
Table 7. Summary of Estimated Reductions.............................................................................26
Table 8. TMDL Reductions for Fecal Coliform .......................................................................29
Table 9. Relative Fecal Coliform Contributions Rates.............................................................29
Table 10. Richland Creek and Muddy Creek TMDL Components ........................................30
Table 11. NCDENR Ambient Monitoring Data for Richland Creek (1997-2000).................50
Table 12. NCDENR Special Study Monitoring Data for Richland Creek and Muddy Creek
(2003) 51
Table 13. UCFRBA Monitoring Data for Richland Creek and Muddy Creek (2000-2003)...51
Table 14. Richland Creek at Riverdale Road: Estimation of Load Reduction (#/day) Based
on Fecal Coliform Instantaneous Standard............................................................................56
Table 15. Richland Creek at Riverdale Road: Estimation of Load Reduction (#/day) Based
on Fecal Coliform Geometric Mean Standard.......................................................................56
Table 16. Muddy Creek at Muddy Creek Road: Estimation of Load Reduction (#/day)
Based on Fecal Coliform Instantaneous Standard .................................................................57
Table 17. Muddy Creek at Muddy Creek Road: Estimation of Load Reduction (#/day)
Based on Fecal Coliform Geometric Mean Standard ............................................................57
Table 18. Estimates of Fecal Coliform Loading Rates for Urban and Rural Lands ...............58
Table 19. Estimates of Direct Fecal Coliform Contribution from Urban Sources..................58
Table 20. Relative Urban and Rural Fecal Coliform Areal Loading for Richland Creek.......58
Table 21. Relative Urban and Rural Fecal Coliform Areal Loading for Muddy Creek..........59

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List of Figures
Figure 1. Location of Richland Creek and Muddy Creek ........................................................1
Figure 2. Richland Creek and Muddy Creek NLCD Landuse..................................................4
Figure 3. NCDENR and UCFRBA Monitoring Locations.......................................................6
Figure 4. Richland Creek Monitoring Data May 1 through July 2, 2003.................................7
Figure 5. Muddy Creek Monitoring Data May 1 through July 2, 20031 ..................................7
Figure 6. Comparison of Farm and Housing Unit Density between 1990 and 2000 (U.S.
Census) 11
Figure 7. Comparison of Population Change between 1990 and 2000 and Septic Tank
Density in 1990 According to the 1990 and 2000 U.S. Census.............................................13
Figure 8. Locations of NPDES Point Sources Permitted to Discharge Fecal Coliform.........15
Figure 9. Flow-Duration Curve for NCDENR and UCFRBA Fecal Coliform Data for
Richland Creek at Baker Road (4/27/00 through 7/02/03)....................................................19
Figure 10. Flow-Duration Curve for NCDENR Fecal Coliform Data for Richland Creek at
Riverdale Road (10/23/97 through 7/02/03)..........................................................................19
Figure 11. Flow-Duration Curve for NCDENR Fecal Coliform Data for Muddy Creek
Stations MC1, MC2, and MC3 (2003)..................................................................................20
Figure 12. Flow-Duration Curve for NCDENR Fecal Coliform Data for Muddy Creek at
Cedar Square Road (4/27/00 through 6/5/03)........................................................................20
Figure 13. Instantaneous Fecal Coliform Load-Duration Curve for Richland Creek at
Riverdale Road.......................................................................................................................21
Figure 14. Geometric Mean Fecal Coliform Load-Duration Curves for Richland Creek at
Riverdale Road.......................................................................................................................22
Figure 15. Instantaneous Fecal Coliform Load-Duration Curve for Muddy Creek at Muddy
Creek Road (MC2).................................................................................................................22
Figure 16. Geometric Mean Fecal Coliform Load-Duration Curves for Muddy Creek at
Muddy Creek Road (MC2)....................................................................................................23
Figure 17. Instantaneous Fecal Coliform Load-Duration Curve for Muddy Creek at SR 1936
(MC3) 23
Figure 18. Geometric Mean Fecal Coliform Load-Duration Curves for Muddy Creek at SR
1936 (MC3)............................................................................................................................24
Figure 19. TMDL Curve Based on Instantaneous Fecal Coliform Standard for Richland Creek
at Riverdale Road, Exceedances Circled ...............................................................................27
Figure 20. TMDL Curve Based on Geometric Mean Fecal Coliform Standard for Richland
Creek at Riverdale Road, Exceedances Circled.....................................................................27
Figure 21. TMDL Curve Based on Instantaneous Fecal Coliform Standard for Muddy Creek
at Muddy Creek Road, Exceedances Circled.........................................................................28
Figure 22. TMDL Curve Based on Geometric Mean Fecal Coliform Standard for Muddy
Creek at Muddy Creek Road, Exceedances Circled..............................................................28

Richland Creek and Muddy Creek TMDLs March 2004

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SUMMARY SHEET
Total Maximum Daily Load (TMDL)

1. 303(d) Listed Waterbody Information
State: North Carolina
County: Guilford and Randolph
Major River Basin: Cape Fear River Basin
Watershed: Richland Creek and Muddy Creek in Deep River Watershed HUC 03030003

Impaired Waterbody (2002 303(d) List):
Waterbody Name - (ID) Water Quality Classification Impairment Length (mi)
Richland Creek - 17-7-(0.5) WS-IV - Aquatic life and
secondary contact recreation Fecal Coliform 6.4
Richland Creek - 17-7-(4) WS-IV CA- Aquatic life and
secondary contact recreation Fecal Coliform 2.6
Muddy Creek - 17-9-(1) WS-IV - Aquatic life and
secondary contact recreation Fecal Coliform 5.6
Muddy Creek – 17-9-(2) WS-IV CA- Aquatic life and
secondary contact recreation Fecal Coliform 0.5

Constituent(s) of Concern: Fecal Coliform Bacteria
Designated Uses: Biological integrity, propagation of aquatic life, and recreation.
Applicable Water Quality Standards for Class C Waters:
Fecal coliforms shall not exceed a geometric mean of 200/100mL (membrane filter count) based
upon at least five consecutive samples examined during any 30 day period, nor exceed 400/100 mL
in more than 20 percent of the samples examined during such period.
2. TMDL Development
Analysis/Modeling:
Load duration curves based on cumulative frequency distribution of flow conditions in the
watershed. Allowable loads are average loads over the recurrence interval between the 95th and 10th
percent flow exceeded (excludes extreme drought (>95th percentile) and floods (<10th percentile)).
Percent reductions expressed as the average value between existing loads (calculated using an
equation to fit a curve through actual water quality violations) and the allowable load at each
percent flow exceeded.
Critical Conditions:
Critical conditions are accounted for in the load curve analysis by determining the average
difference between the existing load violation trend line and the allowable load line. This approach
was chosen because existing load violations occur at all flow levels.
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Seasonal Variation:
Seasonal variation in hydrology, climatic conditions, and watershed activities are represented
through the use of a continuous flow gage and the use of all readily available water quality data
collected in the watershed.
3. Allocation Watershed/Stream Reach

Segment Pollutant Existing WLA1 LA MOS2 Reduction
Required TMDL
Richland
Creek
Fecal
Coliform 5.47E+11 7.05E+10 2.94E+10 Explicit
10% MOS 82% 9.99E+10
Muddy
Creek
Fecal
Coliform 3.85E+11 2.86E+10 5.01E+10 Explicit
10% MOS 80% 7.87E+10
Notes:
WLA = wasteload allocation, LA = load allocation, MOS = margin of safety
1WLA includes NPDES continuous point sources plus MS4 stormwater load.
2Margin of safety (MOS) equivalent to 10 percent of the target concentration for fecal coliform.

4. Public Notice Date: 2/19/2004
5. Submittal Date: 3/29/2004
6. Establishment Date: 5/17/2004
7. Endangered Species (yes or blank):
8. EPA Lead on TMDL (EPA or blank):
9. TMDL Considers Point Source, Nonpoint Source, or both: both
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1 Introduction
This report presents the development of Total Maximum Daily Loads (TMDLs) for fecal coliform
impairment of Richland Creek and Muddy Creek. Richland Creek and Muddy Creek near High Point,
North Carolina have been placed on the North Carolina 2002 list of impaired waters (the 303(d) list) and
require estimation of a TMDL for fecal coliform to meet the water quality standards specified for WS-IV
and WS-IV CA waters. Richland Creek and Muddy Creek are headwater tributaries to the Deep River,
located within Guilford and Randolph Counties (Figure 1), draining an area of approximately 30 square
miles.
High Point
Archdale
GUILFORD
RANDOLPH
I-85 Bus
I-85
Cedar Square Rd
.
Muddy Creek Rd.
Weant Rd.
Baker Rd.
US-311
Muddy Creek
Richland Creek
0 1 2 3 4 5 Miles
County Jurisdiction
Non-listed streams
Municipal Boundaries
Roads
USGS 1:24,000 K Hydrography
303(d) listed streams
County Boundary
Future Randleman Reservoir
Watershed Boundaries
N
LEGEND
0 100 200 Miles
Location of Study Area
in the Cape Fear River Basin

Figure 1. Location of Richland Creek and Muddy Creek
1.1 PROBLEM DEFINITION
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. Development of a TMDL
requires an assessment of the assimilative capacity of the stream, assessment of the sources within the
watershed contributing to the total instream load, and a recommendation of the reductions required from
each source.
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1.1.1 TMDL Components
The 303(d) process requires that a 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.
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.
1.1.2 Richland Creek and Muddy Creek Fecal Coliform Impairments
The Richland Creek and Muddy Creek listings are contained in the North Carolina Water Quality
Assessment and Impaired Waters List (2002 Integrated 305(b) and 303(d) Report). The segments of
Richland Creek considered to be impaired due to fecal coliform [Waterbody ID 17-7-(0.5) and 17-7-(4)]
extend 9.0 miles from the headwaters down to the inlet for Randleman Reservoir. The segments of
Muddy Creek considered to be impaired due to fecal coliform [Waterbody ID 17-9-(1) and 17-9-(2)]
extend 6.1 miles from the headwaters down to the inlet for the Muddy Creek arm of Randleman
Reservoir.
Richland Creek and Muddy Creek each have a designated use classification of WS-IV, which is intended
to protect drinking water supplies. This designation also encompasses the more general Class C
requirements that protect aquatic life and secondary contact recreation (NCDENR 2003). The North
Carolina fresh water quality standard for fecal coliform in Class C waters (T15A:02B.0211) states:
Richland Creek and Muddy Creek TMDLs March 2004

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Organisms of the coliform group: fecal coliforms shall not exceed a geometric mean of
200/100 mL (membrane filter count) based upon at least five consecutive samples examined
during any 30 day period, nor exceed 400/100 mL in more than 20 percent of the samples
examined during such period; violations of the fecal coliform standard are expected during
rainfall events and, in some cases, this violation is expected to be caused by uncontrollable
nonpoint source pollution; all coliform concentrations are to be analyzed using the membrane
filter technique unless high turbidity or other adverse conditions necessitate the tube dilution
method; in case of controversy over results, the MPN 5-tube dilution technique will be used as
the reference method.
1.2 WATERSHED DESCRIPTION
Richland Creek and Muddy Creek are located within Guilford and Randolph Counties in North Carolina
(Figure 1). Richland Creek extends 9.0 miles from its headwaters in southern High Point to its entrance
into Randleman Reservoir and includes approximately 43 miles of mainstem and tributary stream reaches.
The creek drains approximately 16 square miles of land, including a portion of the City of High Point.
Muddy Creek extends 6.1 miles from its headwaters in northwestern Archdale to its entrance into the
Muddy Creek Arm of the Randleman Reservoir and includes approximately 40 miles of mainstem and
tributary stream reaches. The creek drains approximately 14 square miles of land, including most of the
City of Archdale.
1.2.1 Landuse Distribution in the Richland Creek and Muddy Creek
Watersheds
The National Land Cover Data (NLCD; USEPA, 2004) were used to determine the landuse distribution
within the watershed. This dataset was developed using satellite data collected during the period from
1992 to1993. Landuse distribution was tabulated for the portions of Richland Creek and Muddy Creek
Watersheds that drain to the 303(d) listed segments. As shown in Table 1 and Figure 2, the upstream half
of each watershed is highly developed, while the downstream portions contain agricultural land and
forest.
The population density within the study area grew from about 630 people per square mile to 660 people
per square mile between 1990 and 2000 (U.S. Census, 1990 and 2000). This small increase in population
indicates that the watersheds have experienced minimal growth and that the NLCD is likely to provide a
relatively accurate description of current residential development. The density of farms has decreased,
which suggests that some agricultural land may have been converted to residential developments. The
conversion of rural landuses will typically shift the nonpoint source contribution of fecal coliform from
agricultural activities such as cattle grazing and manure application to urban sources such as fecal waste
from household pets, sanitary-sewer overflows (SSOs), and leaking sewer lines.
Table 1. Watershed NLCD Landuse Acreage and Percent Composition
Landuse Barren Crop Pasture Other
Grasses Forest Urban Water/
Wetland Total
Richland Creek
Area (ac) 82 915 199 129 3,687 5,211 97 10,321
Area (%) 0.8 8.9 1.9 1.3 35.7 50.5 0.9 100.0
Muddy Creek
Area (ac) 8 1,351 423 64 2,508 2,869 48 7,272
Area (%) 0.1 18.6 5.8 0.9 34.5 39.4 0.7 100.0
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Richland Creek
Muddy Creek
0 1 2 3 Miles
NLCD MRLC Landuse Classification
Barren or Mining
Transitional
Agriculture - Cropland
Agriculture - Pasture
Forest
Upland Shrub Land
Grass Land
LEGEND
Non-listed Streams
USGS 1:24,00 K Hydrography
303(d) Listed Streams
Randleman Reservoir
Watershed Boundaries
Water
Wetlands
Low Intensity Residential
Other Grasses (parks, lawns, etc.)
High Intensity Residential
High Intensity Commercial/Industrial
N
SCALE

Figure 2. Richland Creek and Muddy Creek NLCD Landuse
1.3 WATER QUALITY MONITORING
Water quality monitoring performed by NCDENR for fecal coliform has shown a number of excursions
above the water quality standard. Additional fecal coliform monitoring data, collected by the Upper Cape
Fear River Basin Association (UCFRBA), further supports the decision to list Richland Creek and Muddy
Creek for fecal coliform impairment.
1.3.1 NCDENR Monitoring
Water quality monitoring for Richland Creek and Muddy Creek was performed by NCDENR at two
stations in Richland Creek and three stations in Muddy Creek (Figure 3). Regular monitoring was
performed on Richland Creek at Riverdale Road (B4410000) for the period from 10/23/1997 through
6/28/2000. These data were collected approximately monthly and include observations for fecal coliform.
At all NCDENR stations, intensive fecal coliform monitoring was performed during the period from
5/20/2003 through 7/2/2003 to assess the impairment status with regards to the standards specification
requiring five samples per 30-day period. Table 2 presents a summary of the fecal coliform data
collected.

Richland Creek and Muddy Creek TMDLs March 2004

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Table 2. Summary of NCDENR Water Quality Monitoring for Fecal Coliform Impairment
Station Period Instantaneous
Exceedances/
Observationsa
Geomean
Exceedances/
Observationsb
Richland Creek at
Baker Road 5/03 – 7/03 9/11 7/7
Richland Creek at
Riverdale Road 10/97 – 9/02 12/38 7/12
Muddy Creek at
Weant Road 5/03 – 7/03 9/11 7/7
Muddy Creek at
Muddy Creek Road 5/03 – 7/03 8/11 7/7
Muddy Creek at
SR 1936 5/03 – 7/03 9/11 7/7
a Exceedances (Instantaneous fecal coliform measurements > 400 cfu/100 mL)/Total number of samples
b Exceedances (Geometric mean of 5 fecal coliform measurements within a 30-day period > 200 cfu/100 mL)/Number
of 5-sample groups within a 30-day period
1.3.2 UCFRBA Fecal Monitoring Data
The Upper Cape Fear River Basin Association (UCFRBA) measured fecal coliform concentrations for
Richland Creek at Baker Road and Muddy Creek at Cedar Square Road from 4/27/00 through 6/5/03.
These data are part of an ongoing monitoring program that replaces the in-stream monitoring
requirements of point source dischargers participating with UCFRBA (CFRA, 2003). UCFRBA has a
memorandum of agreement with NCDWQ to conduct this monitoring. A state-approved lab was used to
analyze the fecal coliform samples (Patrick, 2003). A summary of the data collected is presented in
Table 3. The data do not contain any groups of five samples within a 30-day period.
Richland Creek and Muddy Creek TMDLs March 2004

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Richland Creek
Muddy Creek
Baker Rd.
Riverdale Rd.
Weant Rd.
Muddy Creek Rd.
SR 1936
B4410000
MC 1
MC 2
MC 3
Cedar Square Rd.
(UCFRBA only)
SCALE

Monitoring Stations
LEGEND
Watershed Boundaries
Future Randleman Reservoir
County Boundary
303(d) listed streams
USGS 1:24,000 K Hydrography
Roads
Municipal Boundaries
Non-listed streams
County Jurisdiction
1
N
0 1 2 3 4 5 Miles1Construction of the Randleman Dam is complete,
and filling is expected to begin at the end of 2004.
Figure 3. NCDENR and UCFRBA Monitoring Locations

Table 3. Summary of UCFRBA Fecal Coliform Monitoring Data (4/27/00 through 6/5/03)
Station Number of Samples Number Greater Than Standard a
Richland Creek, Baker Road 39 24
Muddy Creek, Cedar Square Road 39 21
a Instantaneous fecal coliform measurements > 400 cfu/100 mL
1.3.3 Summary of Fecal Coliform Trends
The data collected by NCDENR and UCFRBA show an increase in fecal coliform concentrations during
storm events as well as during typical and low flow periods. Since exceedances occur across all flow
regimes, a wide range of sources may contribute to stream impairment. For Richland Creek, high fecal
coliform concentrations at the Baker Road station indicate that urban sources in the headwaters are
contributing to impairment. During the summer of 2003, fecal coliform concentrations at Baker Road
correlated with measurements at Riverdale Road, and the concentrations at the Riverdale Road station
were consistently lower than at the Baker Road station (Figure 4). These results are not surprising as the
flow from each segment contributes to the total flow in the downstream reach. However, it does show
Richland Creek and Muddy Creek TMDLs March 2004

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that the fecal coliform concentrations at Riverdale Road are highly dependent on contributions upstream
of Baker Road and that problems in the headwaters are a major cause of the elevated levels in Richland
Creek.
Fecal coliform concentrations were correlated at each Muddy Creek station during the summer of 2003,
but the upstream effects appear to be less significant than in Richland Creek. None of the stations are
consistently higher than the other stations (Figure 5). Therefore, urban sources appear to contribute to
impairment, but sources in the rural, downstream areas are also likely to be significant.

Richland Creek (Summer 2003) Fecal Coliform Monitoring Data
1
100
10,000
May-2003 Jun-2003 Jul-2003
Date
FC

(
#
/
1
0
0
m
L
)
0
200
400
600
800
1000
1200
1400
1600
1800
2000
Baker Rd.
(NCDENR & PTCOG)
Riverdale Rd.
(B4410000)
Flow at Riverdale Rd.

Figure 4. Richland Creek Monitoring Data May 1 through July 2, 20031

Muddy Creek (Summer 2003) Fecal Coliform Monitoring Data
1
100
10,000
May-2003 Jun-2003 Jul-2003
Date
FC

(
#
/
1
0
0
m
L
)
0
200
400
600
800
1000
1200
1400
1600
1800
2000 Weant Rd. (MC1)
Muddy Creek Rd.
(MC2)
Cedar Square Rd.
(PTCOG)
SR 1936 (MC3)
Flow at SR 1936

Figure 5. Muddy Creek Monitoring Data May 1 through July 2, 20031

1 Flow was estimated from measurements at the USGS East Fork Deep River gage.
1
1
UCFRBA
UCFRBA
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Richland Creek and Muddy Creek TMDLs March 2004

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2 Source Assessment
A critical step in developing a useful and defensible TMDL is the assessment of potential sources. Tetra
Tech performed a watershed-wide review of sources that potentially contribute to high turbidity fecal
coliform loading. This review included data from the National Pollutant Discharge Elimination System,
septic use and public sewer boundaries, and landuse/landcover information. Geographical information
systems and digital orthophotos were used to gain an understanding of the sources within the watershed.
Discussion with local jurisdictions and field personnel were also used to identify and quantify potential
sources.
2.1 GENERAL SOURCES OF FECAL COLIFORM
Both point and nonpoint sources may contribute fecal coliform to the waterbodies. Potential sources of
fecal coliform loading are numerous and often occur in combination. In rural areas, runoff can transport
significant loads of fecal coliform from sources such as agricultural activities and wildlife contributions.
Septic systems, illicit discharges, broken sewer pipes, and stormwater runoff can be potential sources in
urban areas.
Potential sources of fecal coliform loading in the watershed were identified based on an evaluation of
current landuse/cover, septic system/sewer use, and SSO data. The source assessment was used as the
basis of the TMDL allocations.
2.1.1 Nonpoint Source Fecal Coliform Contributions
Research was performed to assess the most probable nonpoint sources of fecal coliform. Information on
sources was gathered from GIS information, census data, and personal communication with local and
state officials. The principal sources investigated were landuse distribution, septic systems, sewer pipe
defects, sanitary sewer overflows, and the populations of wildlife and domestic animals.
Runoff Contributions
Runoff from landuses in the watershed can contribute significant fecal coliform loading to streams.
Stormwater runoff carries wildlife and domestic animal feces from urban areas and fecal coliform from
pasture and other agricultural lands near streams.
A landuse map of the Richland and Muddy Creek watersheds is presented in Figure 2. According to the
landuse data, the watersheds can be divided roughly into two halves: the urban, upstream portions, and
the rural, downstream portions. In the early 1990s when the landuse data were developed, forest
comprised about 35 percent of both watersheds. In the Richland Creek watershed, about half of the
watershed drained developed areas, including low intensity residential, high intensity urban, and
commercial/industrial areas. The Muddy Creek watershed was about 40 percent developed, with most
development in low intensity residential (23 percent). Muddy Creek also drains more farmland than
Richland Creek; about one-tenth of Richland Creek watershed contained agricultural land whereas about
one-quarter of Muddy Creek contained agricultural land.
Review of census data (Figure 6) shows that the density of housing units in the watersheds has not
changed dramatically between 1990 and 2000. The 2000 distribution of housing units confirms that the
urban area boundaries have remained fairly constant in both watersheds. A comparison of agricultural
census data between 1990 and 2000 shows that farming has declined in both watersheds (Figure 6). It is
likely that some livestock operations remain in both watersheds and that these operations may be source
of fecal coliform during wet weather events.
Richland Creek and Muddy Creek TMDLs March 2004

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In the urban, upstream portions of both creeks, the likely sources of runoff fecal coliform loading include
domestic animal feces and wildlife such as geese that populate the golf courses. In the rural, downstream
portions of Richland Creek and Muddy Creek, fecal coliform loading may be caused by domestic
animals, agricultural practices, or wildlife.
Although Richland Creek and Muddy Creek share similar upstream and downstream landuse trends, the
two watersheds differ by the density of urban and agricultural landuses. The Richland Creek watershed
contains higher housing densities than Muddy Creek. Higher housing densities may lead to more fecal
coliform loading from pets and more frequent sanitary sewer overflows (SSOs) during storm events.
Richland Creek and its tributaries also flow through golf courses and parks, and geese populations
attracted by these open spaces may contribute fecal coliform to urban runoff. As discussed in Section
1.3.3, the monitoring data indicate that much of the fecal coliform loading to Richland Creek originates in
upstream reaches. Accordingly, the downstream, rural areas likely contribute less to fecal coliform
impairment than the upstream, urban sources since high and transition flow exceedances are less frequent
at Riverdale Road than at Baker Road (Figure 9 and Figure 10). In addition, the downstream portion of
Richland Creek had a fairly contiguous forested buffer in the early 1990s. If this forest remains, the
stream would be buffered from some of the residential and agricultural runoff, suggesting that wildlife is
the more important wet weather source in the downstream portion of the watershed.
The effects of urban landuse on Muddy Creek impairment appear to be less pronounced than for Richland
Creek. Since its urban density is lower than High Point, the City of Archdale may experience less
frequent SSOs, have smaller geese populations or have lower residential densities. Despite these
differences, urban runoff remains a factor in Muddy Creek. Directly downstream of the urban area,
instream concentrations are elevated, especially above the Weant Road monitoring station. In the rural
portion of Muddy Creek, wet weather fecal coliform loading may be caused by manure application to
cropland, cattle access to streams, or low density residential areas with pets. Agricultural land had
encroached significantly into the riparian corridor in the 1990s, which may point to agriculture rather than
wildlife is a more important source of fecal coliform during storm events. Unlike Richland Creek, high
and transition flow fecal coliform exceedances in Muddy Creek do not decrease in frequency from
upstream to downstream (Figure 4). The landuse and monitoring data indicate that while urban runoff is
the major source of wet weather loading in Richland Creek, both urban and agricultural runoff may
contribute fecal coliform to Muddy Creek.

Richland Creek and Muddy Creek TMDLs March 2004

11



Richland Creek
Muddy Creek


Richland Creek
Muddy Creek
Density of Housing Units with Farms (unit/ sq. mile)
0
0.1 - 0.4
0.5 - 0.9
1 - 2
USGS 1:24,000 Hydrography
303d Listed Segments
County Boundary
Monitoring Locations
Watershed Boundaries
LEGEND
Farm Density
20001990
SCALE
N
0 0.5 1 1.5 2 Miles


Richland Creek
Muddy Creek


Richland Creek
Muddy Creek
USGS 1:24,000 Hydrography
303d Listed Segments
County Boundary
Monitoring Locations
Watershed Boundaries
LEGEND
Density of Housing Units
1990 2000
0 0.5 1 1.5 2 Miles
N
SCALE
Housing Unit Denstiy (unit/sq. mile)
40 - 499
500 - 999
1,000 - 1,999
2,000 - 2,999
3,000 - 4,864
Baker Road
Baker Road
Baker Road Baker Road
WeantRoad
WeantRoad
WeantRoad WeantRoad

Figure 6. Comparison of Farm and Housing Unit Density between 1990 and 2000 (U.S. Census)
Richland Creek and Muddy Creek TMDLs March 2004

12
Septic Systems
Septic tanks are one of several possible causes of low flow exceedances. Other sources of low flow fecal
coliform loading are leaking sewer pipes, illicit discharges, and other direct inputs of raw sewage.
Figure 7 shows the density of septic system use throughout the watersheds according to the 1990 census.
The use of septic systems was concentrated in the downstream half of both watersheds in 1990, although
some septic systems were being used in the urban areas. Since septic system use data was not included in
the 2000 census, population growth was used to assess how septic tank use has changed over the decade.
The comparison of population densities between 1990 and 2000 in Figure 7 shows that most of the
population growth has occurred south of High Point in the headwaters of Richland Creek and east of
Archdale upstream of the Muddy Creek Road monitoring station. Few septic systems were found south
of High Point in 1990, and it is likely that new households are using sanitary sewers. Only a small
amount of growth occurred in the downstream portions of Richland Creek and Muddy Creek, and the use
of septic systems has probably remained similar to 1990 levels.
In Richland Creek, low flow exceedances have only been measured at the Baker Road monitoring stations
(Figure 9). Septic systems are one possible source of low flow fecal coliform loading in the urban,
upstream portion of Richland Creek since some septic tanks may remain in downtown High Point. Older
septic systems, like sand filters, may be responsible for a large portion of the fecal coliform loading,
depending on their location and condition. Other likely low flow sources are sewer pipe defects.
For Muddy Creek, the UCFRBA data at Cedar Square Road are the only monitoring data collected during
low flow events. At Cedar Square Road, a few low flow exceedances were measured. Since this station
is located downstream of the 303(d) listed reach, both urban and rural sources could be contributing to the
low flow events. Septic systems throughout the watershed are one possible source of low flow fecal
coliform loading. According to the Randolph County Health Department, the public sewer system has
only been extended to a few subdivisions west of Archdale (Walker, 2003). Otherwise, the majority of
households outside of Archdale “proper” continue to use septic systems. Contribution of fecal coliform
by septic systems could explain the low flow exceedances at the Muddy Creek monitoring stations.

Richland Creek and Muddy Creek TMDLs March 2004

13


Richland Creek
Muddy Creek


Richland Creek
Muddy Creek


Richland Creek
Muddy Creek
Population Density (persons/ sq.mile)
1990 2000
Population Density
Density of Housing Units on Septic Tanks
Density of Housing Units
on Septic Tanks (unit/ sq.mile)
0 - 9
10 - 24.5
25 - 99
100 - 199
200 - 400
USGS 1:24,000 Hydrography
303d Listed Segments
County Boundary
Monitoring Locations
Watershed Boundaries
LEGEND
LEGEND
0 1 2 Miles
N
0 0.5 1 1.5 Miles
N
USGS 1:24,000 Hydrography
303d Listed Segments
County Boundary
Monitoring Locations
Watershed Boundaries
SCALE
SCALE
169 - 499
500 - 999
1,000 - 1,999
2,000 - 2,999
3,000 - 3,999
4,000 - 4,999
5,000 - 5,999
6,000 - 11,000
Baker Road
Baker Road
Baker Road
WeantRoad
Weant
Road
WeantRoad

Figure 7. Comparison of Population Change between 1990 and 2000 and Septic Tank Density in
1990 According to the 1990 and 2000 U.S. Census
Richland Creek and Muddy Creek TMDLs March 2004

14
Sewer Overflows
Fecal coliform may enter surface water when sewer pipes are clogged, damaged, or flooded by
stormwater. Infiltration of rainfall can enter the sewer system through cracks and leaks in pipes. This
additional flow volume, in combination with the existing sewer flow, can exceed the capacity of the
system resulting in a sanitary-sewer-overflow (SSO).
Based on data provided by NC DWQ, sixteen SSO events have been reported in High Point during the
last two years (Mauney, 2003). Of these sixteen events, ten contributed less than 5,000 gallons or were
single occurrences at the discharge location. However, six relatively significant events ranging from
18,000 to 318, 590 gallons occurred near 5745 Riverdale Road. The Riverdale Road overflows may
constitute a significant, reoccurring source contributing to fecal coliform impairment in Richland Creek.
The City of Archdale does not have any SSOs on record within the past three years (Shuler, 2003). A lift
station is located on Weant Road in Muddy Creek and may be a source of high flow fecal coliform
loading to Muddy Creek.
Sewer Defects
Defects in sewer pipes, including cracked and corroded pipes, allow sewage to leak into surface water.
Sewer pipe leaks are a likely cause of low flow fecal coliform exceedances as they contribute high loads
during periods where there is a minimal amount of stream flow to dilute their contribution. Richland and
Muddy Creeks drain some of the oldest sections of the High Point and Archdale, where sewer pipes may
have developed cracks and corrosion over many years of use. The city officials are not aware of any
specific location of sewer defects (Shuler, 2003; Hepler, 2003). The wide range of flows during which
exceedances occur and the elevated levels in the urban areas suggest that sewer defects are potentially a
very significant problem.
2.1.2 Point Source Fecal Coliform Contributions
Two low-scale wastewater treatment plants, termed “package plants,” are permitted to discharge into the
Muddy River and its tributaries within the listed segment (Figure 8). Table 4 presents the average flow,
loading, and permit limits for the NPDES facilities discharging fecal coliform to Muddy Creek. Some of
the facilities may need to be repaired or upgraded (Mauney, 2003; Walker, 2003). These plants are
potential causes of high fecal coliform measurements at MC1 (Weant Road) and MC2 (Muddy Creek
Road) during all flow regimes. At present, only the Penman Heights facility is discharging to the Muddy
Creek watershed. This facility discharges to a tributary a quarter mile from Muddy Creek between
stations MC1 and MC2.
As discussed in the source assessment, urban stormwater runoff can contribute fecal coliform to Richland
Creek and Muddy Creek. Much of this runoff is considered a point source and is regulated in compliance
with the Storm Water Phase II Final Rule (EPA, 2000). This rule applies to a unit of government such as
a city or county, which owns or operates a municipal separate storm sewer system (MS4). The MS4 is
required to obtain a National Point Source Discharge Elimination System (NPDES) permit for their
stormwater discharges to surface waters. As such, stormwater runoff from areas within an MS4 is
considered a point source. The City of High Point, the City of Archdale, and Guilford County fall under
the Phase II Rule and therefore maintain stormwater management programs. Loadings of fecal coliform
from stormwater runoff are considered to be point source discharges for the purpose of the TMDL.
Richland Creek and Muddy Creek TMDLs March 2004

15
Table 4. NPDES Facilities Discharging Fecal Coliform
NPDES Permit Limits
Facility Name NPDES Permit
No. Permitted Avg.
Flow (MGD)
Fecal Coliform
Loading
Geomean
(#/100mL)
Fecal Coliform
Loading
Maximum
(#/100mL)
Status
Penman Heights NC0055191 0.0250 200 400 Active
Rimmer Mobile
Home Court NC0069451 0.0204 200 400 Not active










High Point
Archdale
GUILFORD
RANDOLPH
MC 2
Riverdale Rd.
Muddy Creek
Richland Creek
MC 1
Baker Rd.
County Jurisdiction
Non-listed streams
Municipal Boundaries
Roads
USGS 1:24,000 K Hydrography
303(d) listed streams
County Boundary
Watershed Boundaries
LEGEND
NPDES Point Sources

Monitoring Stations
0 1 2 3 4 Miles
N

Figure 8. Locations of NPDES Point Sources Permitted to Discharge Fecal Coliform
Richland Creek and Muddy Creek TMDLs March 2004

16
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Richland Creek and Muddy Creek TMDLs March 2004

17
3 Technical Approach
Given the results of the initial data analysis and time and budget constraints, an approach focusing on the
magnitude of water quality standard exceedances and potential sources contributing to the stream during
the exceedances was used. This approach used a flow-duration curve analysis to determine the flow
conditions under which impairment occurs. In addition, the approach was used to identify source types,
specify the assimilative capacity of the stream, and estimate the magnitude of load reduction required to
meet the water quality standards. The potential sources determined from the load-duration curve were
inventoried and assessed for their relative contributions to allocate reductions among sources. The results
of this assessment were used to derive the allocations required by the TMDL.
This section describes the process used to specify the endpoints and calculate the existing loading and
assimilative capacity. The determination of the TMDL reductions and loads are presented in Section 4.
3.1 TMDL ENDPOINTS
The achievement of the TMDL objectives require the instream concentrations to meet both the
instantaneous standard of 400 cfu/100 mL and the geometric mean standard of 200 cfu/100 mL. Both
standards are considered to be the endpoints for the determination of the fecal coliform TMDL for the
Richland Creek and Muddy Creek.
3.2 FLOW-DURATION CURVES FOR FECAL COLIFORM
The analysis of pollutant levels in conjunction with water quality standards and measured flow is a useful
tool for assessing critical conditions, as well as existing and target loads. The Flow-Duration Curve
Method (Stiles 2002, Cleland 2002) was used for fecal coliform. This method plots flow and observed
data to analyze the flow conditions under which impairment occurs and water quality deviates from the
standard. The method was used to determine the seasonality and flow regimes during which the
exceedances occur and to determine maximum daily load based on the flow duration and applicable
standard.
A flow-duration curve analysis was performed to identify the flow regimes during which exceedances of
the water quality standards occur. This method determines the relative ranking of a given flow based on
the percent of time that historic flows exceed that value. The flow gage nearest to Richland and Muddy
Creeks was USGS Station 02099000 on the East Fork of the Deep River. This gage is about ten miles
upstream of Richland Creek on the Deep River and drains a watershed with a similar landuse distribution.
Flow statistics for the gage are presented in Table 5. Since no flow gages were on Richland Creek or
Muddy Creek, the flow data from USGS Station 02099000 were scaled to each monitoring station based
on drainage area using the proportions in Table 6. These proportions represent the ratio of monitoring
station drainage area to gauging station drainage area. Daily gauging data for the period from 1/1929
through 12/2002 was multiplied by these proportions and used to establish the historic flow regimes and
ranges for the high, transitional, typical, and low flow conditions.
Richland Creek and Muddy Creek TMDLs March 2004

18
Table 5. Flow Statistics for USGS Gage 02099000
Flow Parameter Value (cfs)
Mean 17.4
Min 0.6
Max 1670.0
High flow range 26.0 – 1,670.0
Transitional flow range 12.0 – 26.0
Typical flow range 4.7 – 12.0
Low flow range 0.6 – 4.7

Table 6. Relative Proportion of Flow at USGS Gage 02099000 (East Fork Deep River) for Each
Monitoring Station Drainage Area
Stream Station Relative Proportion of Gage Flow
Richland Creek Baker Road 0.57
Richland Creek Riverdale Road 1.10
Muddy Creek Weant Rd 0.58
Muddy Creek Muddy Creek Road 0.99
Muddy Creek Cedar Square Road 1.14
Muddy Creek SR 1936 1.80

Once the relative rankings were calculated for flow, monitoring data were matched by date to compare
observed water quality to the flow regime during which it was collected. This type of analysis can help
define the flow regime during which exceedances occur and also pinpoint the source of the impairment.
Exceedances that occur only during low-flow events are likely caused by continuous or point source
discharges, which are generally diluted during storm events. Exceedances that occur during high-flow
events are generally driven by storm-event runoff. A mixture of point and nonpoint sources may cause
exceedances during normal flows.
In Figure 9 through Figure 12, the flow-duration analysis is presented for the six monitoring stations in
the study area. All stations show exceedances of the instantaneous-fecal-coliform water quality standard
(400 cfu/100 mL) during high-flow and typical-flow regimes, indicating contributions from moderate and
high-flow-storm events as well as some intermittent discharges. Fecal coliform concentrations are
expressed as number of colony forming units and may be written as “#/100 mL” or “cfu/100 mL.”
Figure 9 and Figure 12 indicate that while many exceedances occur during high and transition-flow
events, fecal coliform also exceeds the instantaneous standard during typical and low flows. The data
suggest that both storm-event runoff and low-flow sources, such as illicit discharges, septic systems, or
broken sewer lines, contribute to high fecal coliform loading. It should be noted that Cedar Square Road
is the only Muddy Creek station where low flow measurements are available.
Richland Creek and Muddy Creek TMDLs March 2004

19
Richland Creek at Baker Road
WQ Duration Curve (NCDENR and UCFRBA Monitoring Data)
1
10
100
1000
10000
100000
0 10 20 30 40 50 60 70 80 90 100
Flow Duration Interval (%)
Fe
c
a
l

c
o
l
i
f
o
r
m
,

c
f
u
/
1
0
0
m
L
NCDENR
UCFRBA
WQ Standard
Geo mean
Low flowsTypical
High Transition
DroughtFlood

Figure 9. Flow-Duration Curve for NCDENR and UCFRBA Fecal Coliform Data for Richland Creek
at Baker Road (4/27/00 through 7/02/03)

Richland Creek at Riverdale Road (B4410000)
WQ Duration Curve (NCDENR)
1
10
100
1000
10000
100000
0 10 20 30 40 50 60 70 80 90 100
Flow Duration Interval (%)
Fe
c
a
l

c
o
l
i
f
o
r
m
,

c
f
u
/
1
0
0
m
L
NCDENR
WQ Standard
Geo mean
Low flowsTypical
High Transition
DroughtFlood

Figure 10. Flow-Duration Curve for NCDENR Fecal Coliform Data for Richland Creek at Riverdale
Road (10/23/97 through 7/02/03)
Richland Creek and Muddy Creek TMDLs March 2004

20
Muddy Creek NCDENR Monitoring Data
WQ Duration Curve
1
10
100
1000
10000
100000
0 10 20 30 40 50 60 70 80 90 100
Flow Duration Interval (%)
Fe
c
a
l

c
o
l
i
f
o
r
m

(
#
/
1
0
0
m
L
)
WQ Standard
Weant Rd. (MC1)
Muddy Creek Rd. (MC2)
SR 1936 (MC3)
Low flowsTypical flowsHigh
flo ws
Transition
flows
DroughtFlood

Figure 11. Flow-Duration Curve for NCDENR Fecal Coliform Data for Muddy Creek Stations
MC1, MC2, and MC3 (2003)
Muddy Creek at Cedar Square Rd.
WQ Duration Curve (UCFRBA Monitoring Data)
1
10
100
1000
10000
0 10 20 30 40 50 60 70 80 90 100
Flow Duration Interval (%)
Fe
c
a
l

c
o
l
i
f
o
r
m
,

c
f
u
/
1
0
0
m
L
UCFRBA
WQ Standard
Geo mean
Low flowsTypical
High Transition
DroughtFlood

Figure 12. Flow-Duration Curve for NCDENR Fecal Coliform Data for Muddy Creek at Cedar
Square Road (4/27/00 through 6/5/03)
Richland Creek and Muddy Creek TMDLs March 2004

21
3.3 DETERMINATION OF EXISTING FECAL COLIFORM LOAD AND
ASSIMILATIVE CAPACITY
The fecal coliform assessment uses the Flow-Duration Curve approach for determination of the existing
load and assimilative capacity. The analysis was performed for both the instantaneous and geometric
mean standard to determine the most conservative measure of impairment. Figure 13 through Figure 18
present the results of the instantaneous and geometric mean load-duration analyses based on NCDENR
data collected for Richland Creek at Riverdale Road and for Muddy Creek at Muddy Creek Road and
State Road 1936. The average of the five flow observations corresponding to the five fecal coliform
sample dates was used as the flow for each geometric mean load.
The load-duration curves developed in this section provide guidance in the determination of the pollutant
sources that are likely to be the primary contributors to elevated levels of fecal coliform. For example,
elevated fecal coliform levels that occur only during typical and high flow events are not likely to be
caused by continuously discharging sources, such as failing septic systems. Nonpoint sources and
sporadic sources such as sanitary sewer overflows are likely to be the main focus of the inventory in this
case.
Richland Creek at Riverdale Rd. (B410000)
FC Instantaneous
Load Duration Curve
1.0E+08
1.0E+09
1.0E+10
1.0E+11
1.0E+12
1.0E+13
1.0E+14
0 10 20 30 40 50 60 70 80 90 100
Flow Duration Interval (%)
FC

(
#
/
d
a
y
)
NCDENR Ambient
NCDENR Special Study
FC Inst Limit Curve

Figure 13. Instantaneous Fecal Coliform Load-Duration Curve for Richland Creek at Riverdale
Road
Richland Creek and Muddy Creek TMDLs March 2004

22
Richland Creek at Riverdale Rd.
FC Geomean
Load Duration Curve
1.0E+08
1.0E+09
1.0E+10
1.0E+11
1.0E+12
1.0E+13
0 10 20 30 40 50 60 70 80 90 100
Flow Duration Interval (%)
FC

(
#
/
d
a
y
)
NCDENR Special Study
FC Geo Limit Curve

Figure 14. Geometric Mean Fecal Coliform Load-Duration Curves for Richland Creek at
Riverdale Road
Muddy Creek at Muddy Creek Rd. (MC2)
FC Instantaneous
Load Duration Curve
1.0E+08
1.0E+09
1.0E+10
1.0E+11
1.0E+12
1.0E+13
1.0E+14
0 20 40 60 80 100
Flow Duration Interval (%)
FC

(
#
/
d
a
y
)
NCDENR Special Study
FC Inst Limit Curve

Figure 15. Instantaneous Fecal Coliform Load-Duration Curve for Muddy Creek at Muddy Creek
Road (MC2)
Richland Creek and Muddy Creek TMDLs March 2004

23
Muddy Creek at Muddy Creek Rd. (MC2)
FC Geomean
Load Duration Curve
1.0E+08
1.0E+09
1.0E+10
1.0E+11
1.0E+12
1.0E+13
0 20 40 60 80 100
Flow Duration Interval (%)
FC

(
#
/
d
a
y
)
NCDENR Special Study
FC Geo Limit Curve

Figure 16. Geometric Mean Fecal Coliform Load-Duration Curves for Muddy Creek at Muddy
Creek Road (MC2)

Muddy Creek at SR 1936 (MC3)
FC Instantaneous
Load Duration Curve
1.0E+08
1.0E+09
1.0E+10
1.0E+11
1.0E+12
1.0E+13
1.0E+14
0 20 40 60 80 100
Flow Duration Interval (%)
FC

(
#
/
d
a
y
)
NCDENR Special Study
FC Inst Limit Curve

Figure 17. Instantaneous Fecal Coliform Load-Duration Curve for Muddy Creek at SR 1936 (MC3)
Richland Creek and Muddy Creek TMDLs March 2004

24
Muddy Creek at SR 1936 (MC3)
FC Geomean
Load Duration Curve
1.0E+08
1.0E+09
1.0E+10
1.0E+11
1.0E+12
1.0E+13
0 20 40 60 80 100
Flow Duration Interval (%)
FC

(
#
/
d
a
y
)
NCDENR Special Study
FC Geo Limit Curve

Figure 18. Geometric Mean Fecal Coliform Load-Duration Curves for Muddy Creek at
SR 1936 (MC3)
Richland Creek and Muddy Creek TMDLs March 2004

25
4 TMDL Development
Sections 1 through 3 described the processes and rationale required to identify the endpoints, critical
conditions, potential sources, and target loadings for each pollutant. These efforts formed the basis for
the TMDL process. This section describes the key components required by the TMDL guidelines and
synthesizes the project efforts to set the final TMDL allocations.
4.1 TMDL DEFINITION
A TMDL is the total amount of a pollutant that can be assimilated by the receiving water while still
achieving water quality criteria (in this case a target for warm water aquatic habitat). TMDLs can be
expressed in terms of mass per time or by other appropriate measures such as concentration. TMDLs are
comprised of the sum of individual wasteload allocations (WLAs) for point sources, load allocations
(LAs) for nonpoint sources, and natural background levels. In addition, the TMDL must include a margin
of safety (MOS), either implicitly or explicitly, that accounts for the uncertainty in the relationship
between pollutant loads and the quality of the receiving waterbody. Conceptually, this definition is
denoted by the equation:

TMDL = Σ WLAs + Σ LAs + MOS

4.2 TMDL ENDPOINTS
TMDL endpoints represent the instream water quality targets used in quantifying TMDLs and their
individual components. As discussed in Section 3, there are two endpoints that will be used to determine
the fecal coliform TMDL, as specified in the North Carolina water quality standards. Both the
instantaneous limit of 400 cfu/100 mL and the geometric mean of 200 cfu/100 mL will be considered.
4.3 CRITICAL CONDITIONS
Based on the load-duration curves, the greatest frequency of exceedances for fecal coliform occur during
the summer period. The Load-Duration-Curve approach addresses the load reductions required during all
flow regimes and all seasons.
4.4 SEASONAL VARIATIONS
Seasonal variation is considered in the development of the TMDLs because the allocation applies to all
seasons. As noted in the critical conditions section, the majority of the exceedances occur during the
summer months.
4.5 MARGIN OF SAFETY (MOS)
There are two methods for incorporating a MOS in the analysis: 1) by implicitly incorporating the MOS
using conservative model assumptions to develop allocations; or 2) by explicitly specifying a portion of
the TMDLs as the MOS and using the remainder for allocations. For the purposes of this analysis, an
explicit 10 percent margin of safety was specified.
Richland Creek and Muddy Creek TMDLs March 2004

26
4.6 TMDL CURVES
The load-duration curves presented in Section 3.3 provide the basis for the reductions required to meet the
TMDL targets. Allowable load curves were calculated using the water quality standards and a 10% MOS.
Based on guidance from EPA Region 4 and NCDENR, data collected during extreme drought conditions
(>95th percentile) and floods (<10th percentile) were excluded from the reduction analysis. Load-duration
curves were generated from historical monitoring data and combined flow and observed concentrations to
show the times when the assimilative capacity of the stream was exceeded.
Reductions were first estimated by developing a regression between exceedance points and the flow
interval. At every 5th percentile flow recurrence, the existing loads were calculated from the regression
equation the allowable loadings were calculated from the TMDL target value. Review of the statistical
power of these regressions, however indicated that valid regression curves for existing loading could not
be estimated from the observed data. Therefore, the geomean of the exceedances was used as an estimate
of the existing load.
The allowable loads using the instantaneous standard for each exceedance were calculated based on the
TMDL target value of 360 CFU/100mL. Similarly, for the geomean standard, the allowable loadings
were calculated from the TMDL target value of 180 CFU/100mL. The geomeans of the exceedances and
the allowable loads were used to calculate the percent that the existing load exceeded the target. The
target curves based on the allowable loads and the exceedances used for the existing loads are shown in
Figure 19 through Figure 22.
The loading estimates as well as the average values are presented in Appendix B. A summary of the
estimated reductions required to meet the TMDL target are presented in Table 7. It can be seen that the
instantaneous target is the most stringent for Richland Creek, whereas in Muddy Creek the geometric
mean limit is more stringent at MC2. The target on Muddy Creek is based on MC2 because its location is
likely to be more indicative of future riverine conditions, whereas MC3 is located well within Randleman
Reservoir. Nonetheless, the reductions will apply to the entire watershed.

Table 7. Summary of Estimated Reductions
Stream Pollutant Target Reduction Required
Richland Creek at
Riverdale Road
Fecal coliform
(Instantaneous Limit) <360 cfu/100 mL 82%
Richland Creek at
Riverdale Road
Fecal coliform
(Geometric Mean Limit) <180 cfu/100 mL 55%
Muddy Creek at MC2 Fecal coliform
(Instantaneous Limit) <360 cfu/100 mL 66%
Muddy Creek at MC2 Fecal coliform
(Geometric Mean Limit) <180 cfu/100 mL 80%
Richland Creek and Muddy Creek TMDLs March 2004

27
Richland Creek at Riverdale Rd.
FC Instantaneous
Load Duration Curve
1.0E+08
1.0E+09
1.0E+10
1.0E+11
1.0E+12
1.0E+13
1.0E+14
10 20 30 40 50 60 70 80 90
Flow Duration Interval (%)
FC

(
#
/
d
a
y
)
NCDENR Ambient
NCDENR Special Study
FC Load Limit w ith MOS

Figure 19. TMDL Curve Based on Instantaneous Fecal Coliform Standard for Richland Creek at
Riverdale Road, Exceedances Circled

Richland Creek at Riverdale Rd.
FC Geomean
Load Duration Curve
1.0E+08
1.0E+09
1.0E+10
1.0E+11
1.0E+12
10 20 30 40 50 60 70 80 90
Flow Duration Interval (%)
FC

(
#
/
d
a
y
)
NCDENR Special Study
FC Load Limit w ith MOS

Figure 20. TMDL Curve Based on Geometric Mean Fecal Coliform Standard for Richland Creek at
Riverdale Road, Exceedances Circled

Richland Creek and Muddy Creek TMDLs March 2004

28
Muddy Creek at Muddy Creek Rd. (MC2)
FC Instantaneous
Load Duration Curve
1.0E+08
1.0E+09
1.0E+10
1.0E+11
1.0E+12
1.0E+13
1.0E+14
10 20 30 40 50 60 70 80 90
Flow Duration Interval (%)
FC

(
#
/
d
a
y
)
NCDENR Special Study
FC Load Limit w ith MOS

Figure 21. TMDL Curve Based on Instantaneous Fecal Coliform Standard for Muddy Creek at
Muddy Creek Road, Exceedances Circled

Muddy Creek Rd. (MC2)
FC Geomean
Load Duration Curve
1.0E+08
1.0E+09
1.0E+10
1.0E+11
1.0E+12
10 20 30 40 50 60 70 80 90
Flow Duration Interval (%)
FC

(
#
/
d
a
y
)
NCDENR Special Study
FC Load Limit w ith MOS

Figure 22. TMDL Curve Based on Geometric Mean Fecal Coliform Standard for Muddy Creek at
Muddy Creek Road, Exceedances Circled

Richland Creek and Muddy Creek TMDLs March 2004

29
4.7 TMDL SUMMARY
The load-duration curves for the existing and target conditions were evaluated to determine the reductions
needed to meet the TMDL endpoints. The higher reduction requirement will be selected to provide an
added margin of safety to the TMDL. To achieve the specified TMDL targets, significant reductions
were required. These are summarized in Table 8.
Table 8. TMDL Reductions for Fecal Coliform
Stream Pollutant Target
Existing Load
(#/day)
Target Load
(#/day)
Reduction
Required
Richland Creek Fecal coliform
(Instantaneous Limit) <360 cfu/100 mL 5.47E+11 9.99E+10 82%
Muddy Creek
Fecal coliform
(Geometric Mean
Limit)
<180 cfu/100 mL 3.85E+11 7.87E+10 80%

Further analysis was required to determine the breakdown between point source (WLA) and nonpoint
source (LA) loadings that meet the TMDL objectives. Based on the EPA guidance in regards to the Phase
II Rule, urban stormwater runoff from an MS4 is considered as a WLA component.
The entire Richland Creek watershed falls within the Phase II boundaries. Therefore, all fecal loadings
from urban landuses are assigned to the WLA component. Loadings from agricultural and forested areas
are considered as nonpoint sources and are reported as LAs. The distribution of the urban and rural
landuses, 51.3 percent and 48.7 percent respectively, was determined from the NLCD landuse coverage
discussed in Section 2. Similarly, the distribution of urban and rural lands inside and outside of the MS4
areas were determined for Muddy Creek.
The relative loading rates between the urban and rural landuse types was determined based on analysis of
fecal coliform runoff data collected by USGS and summarized in the report Relation of Land Use to
Streamflow and Water Quality at Selected Sites in the City of Charlotte and Mecklenburg County, North
Carolina, 1993-98 (USGS, 1999). Water quality data was collected at nine sites which drained relatively
homogeneous landuses in order to estimate the pollutant yields from each. Average fecal coliform
concentrations were calculated by combining the estimates for the urban and rural watersheds (See
Appendix B). The relative percent contributions of fecal coliform were combined with the landuse
distribution to estimate the overall relative loading ratios for urban (MS4) and rural (non MS4) areas
(Table 9).
Table 9. Relative Fecal Coliform Contributions Rates
Stream Urban (% of Load) Rural (% of Load)
Richland Creek 70 30
Muddy Creek 36 64

The assimilative capacity determined in Section 3.3 was split based on the relative contributions
presented in Table 9 to determine the WLA and LA components. The results of these calculations are
summarized in Table 10.
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Table 10. Richland Creek and Muddy Creek TMDL Components
Segment Pollutant Existing WLA1 LA MOS2 TMDL
Richland
Creek
Fecal coliform
(counts/day) 5.47E+11 7.05E+10 2.94E+10 Explicit 10%
MOS 9.99E+10
Muddy Creek Fecal coliform
(counts/day) 3.85E+11 2.86E+10 5.01E+10 Explicit 10%
MOS 7.87E+10
1WLA includes NPDES continuous point sources (0.035E+10 counts/day) plus MS4 load.
2Margin of safety (MOS) equivalent to 10 percent of the target concentration for fecal coliform.
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5 Report Summary
This report presents the development of Total Maximum Daily Loads (TMDLs) for fecal coliform
impairments of Richland Creek and Muddy Creek near High Point, North Carolina. These waterbodies
were placed on the North Carolina 2002 list of impaired waters (the 303(d) list) for fecal coliform.
Available water quality data were reviewed to determine the frequency of exceedances. The flow-
duration curve method was applied to determine the critical periods and the sources that lead to
exceedances of the standard.
The potential sources determined from the load-duration curve were inventoried, and an assessment of
their relative contributions was used to allocate reductions among sources. A review of fecal coliform
data indicates that urban source contributions, such as leaking sewer-pipes and septic systems, are a
significant source of much of the fecal coliform impairment. Additional fecal coliform loading from
nonpoint sources such as stormwater runoff also appear to contribute to instream concentrations. These
results were used to derive the allocations required by the TMDL. The specified reductions can be
achieved with an increased emphasis on identification and repair of aging sewer and septic systems,
minimization of SSO events, and review of current agricultural manure control practices.
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6 TMDL Implementation Plan
Reductions for fecal coliform should be sought through identification and repair of aging sewer and septic
systems and removal of SSOs. Implementation should also target storm-driven sources such as runoff
from residential areas and agricultural land.
The TMDL analysis was performed using the best data available to specify the fecal coliform reductions
necessary to achieve water quality criteria. The intent of meeting the criteria is to support the designated
use classifications in the watershed. A detailed implementation plan is not included in this TMDL. The
involvement of local governments and agencies will be needed in order to develop an implementation
plan.
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7 Stream Monitoring
Monitoring of Richland and Muddy Creeks will be conducted during the next basinwide cycle following
approval of the TMDL. The continued monitoring of fecal coliform will allow for the evaluation of
progress towards the goal of achieving water quality standards and intended best uses. While the TMDLs
has been set at Riverdale Road on Richland Creek and Muddy Creek Road on Muddy Creek, DWQ will
need to assess whether additional monitoring locations are needed once the Randleman Reservoir is
completed.
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8 Future Efforts
MS4 jurisdictions within the study area are Guilford County, the City of Archdale, and the City of High
Point. Randolph County was not required to have an MS4 permit in 2003. Guilford County submitted its
Phase II MS4 permit application in 2003 and has been enforcing watershed protection since 1984.
According to its permit application and current development ordinance, the county will continue to
enforce the use of stormwater BMPs in water supply watersheds and improve the monitoring of these
BMPs (Guilford County, 2003).
The City of High Point and the City of Archdale submitted applications for Phase II MS4 permits in
March 2003. High Point requires erosion control plans for any land-disturbing activity greater than 1 acre
(City of High Point, 2003). The city began requiring stormwater controls in 1993 (Boone, 2003). The
city requires a watershed development plan for any lot greater than 20,000 square feet (City of High
Point, 2003). The City of Archdale began requiring storm water controls in the mid-1990s (Wells, 2003).
All of the MS4 jurisdictions in the study area enforce state water-supply-watershed development
regulations for Randleman Reservoir. Richland Creek and Muddy Creek drain the General Watershed
Overlay District and the downstream portions of the watersheds include Randleman Reservoir’s Critical
Area.
The City of Archdale and the City of High Point include areas which may have aging infrastructure.
These areas can be significant sources of fecal coliform during low flow periods due to leaking sewers
and during high flow events due to increased infiltration and subsequent sanitary sewer overflows.
Review of past monitoring data and additional monitoring efforts can be used to identify potential
problem areas which require additional maintenance.
The current discharge permits for the NPDES permitted point sources are designed to meet water quality
standards at the end of the pipe. Inspection and enforcement efforts should be continued to ensure that
these limits are being met.
Other potential mechanisms for reduction of fecal coliform include local regulations or ordinances related
to zoning, landuse, or storm water runoff controls. Local governments can provide funding assistance
through general revenues, bond issuance, special taxes, utility fees, and impact fees. Additional
mechanisms may employ concurrent education and outreach, training, technology transfer, and technical
assistance with incentive-based pollutant management measures. The State and local governments will
take the primary lead in the TMDL implementation.
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9 Public Participation
A draft of the TMDL was noticed through various public means, including notification in the local
newspapers, High Point Enterprise and Courier Tribune. DWQ distributed the draft TMDL and public
comment information to known interested parties. The TMDL was available from the Division of Water
Quality’s website at http://h2o.enr.state.nc.us/tmdl/ during the comment period. A public meeting was
held on March 9 to present the TMDL and answer questions. Three people plus DWQ staff attended.
The public comment period lasted from February 19, 2004 to March 22, 2004. No comments were
received.
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10 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 and Project Manager
e-mail: [e-mail]
Michelle Woolfolk, Supervisor
e-mail: [e-mail]

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11 References
Boone, Derrick. 2003. City of High Point, North Carolina (personal communication).
CFRA, 2003. Cape Fear River Association: Upper Cape Fear River Basin Association. http://www.cfra-
nc.org/ucfrba.htm
City of High Point. 2003. City of High Point Stormwater Management Program Report.
Cleland, B.R. 2002. TMDL Development from the “Bottom Up” – Part II: Using load duration curves to
connect the pieces. Proceedings from the WEF National TMDL Science and Policy 2002 Conference.
Guilford County. 1995. Forecast 2015: Guilford County Atlas. Guilford County, North Carolina.
Guilford County. 2003. Comprehensive Stormwater Management Program.
http://www.co.guilford.nc.us/government/planning1/wshome.html
Hepler, Bart. 2003. City of High Point, North Carolina (personal communication).
Mauney, Steve. 2003. Division of Water Quality, North Carolina Department of Environment and
Natural Resources, Winston-Salem Regional Office (personal communication).
Patrick, Carol. 2003. Piedmont Triad Council of Governments (personal communication).
Shuler, Michael. 2003. City of Archdale Public Works (personal communication).
Stiles, T.C. 2002. Incorporating hydrology in determining TMDL endpoints and allocations.
Proceedings from the WEF National TMDL Science and Policy 2002 Conference.
U.S. Census Bureau. 1990. 1990 Census of Population and Housing.
http://govinfo.library.orst.edu/index.html (April, 2002).
U.S. Census Bureau. 2000. Census 2000 Summary File. http://factfinder.census.gov
USDA 2002. United States Department of Agriculture. Census Data. http://www.nass.usda.gov/census/
USEPA. 1991. Guidance for Water Quality-Based Decisions: The TMDL Process. U. S. Environmental
Protection Agency, Assessment and Watershed Protection Division, Washington, DC.

USEPA. 1998. Federal Advisory Committee (FACA). Draft final TMDL Federal Advisory Committee
Report.
USEPA. 1999. Protocol for Developing Nutrient TMDLs. 1st ed. EPA 841-B-99-007. U. S.
Environmental Protection Agency; Assessment and Watershed Protection Division.
USEPA 2000. 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.
USEPA 2004. National Land Cover Data. Multi-Resolution Land Characteristics Consortium.
http://www.epa.gov/mrlc/nlcd.html.
USGS. 1999. Relation of Land Use to Streamflow and Water Quality at Selected Sites in the City of
Charlotte and Mecklenburg County, North Carolina, 1993-98. Water Resources Investigations Report 99-
4180. Raleigh, NC.
USGS. 2001. Water Resources of the United States. NWIS-web online hydrologic data:
http://water.usgs.gov (April, 2002).
Richland Creek and Muddy Creek TMDLs March 2004

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Walker, Michael. 2003. Randolph County Health Department, North Carolina (personal
communication).
Wells, Jeff. 2003. City of Archdale Planning Department, North Carolina (personal communication).

Richland Creek and Muddy Creek TMDLs March 2004

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12 Appendices
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APPENDIX A WATER QUALITY SAMPLING DATA
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Table 11. NCDENR Ambient Monitoring Data for Richland Creek (1997-2000)
Date Flow (cfs)a Flow Regime (%)
Riverdale Road
(#/100 mL)
10/23/1997 9.0 38.0 470
11/19/1997 8.8 38.3 10
12/17/1997 7.7 45.7 45
1/26/1998 13.0 24.3 320
2/26/1998 11.0 30.4 10
3/17/1998 9.2 36.7 10
4/22/1998 11.0 30.4 260
5/20/1998 8.2 42.6 81
6/17/1998 8.3 41.0 410
7/16/1998 19.0 14.8 10
8/18/1998 5.9 61.2 130
9/9/1998 9.1 36.7 190
10/14/1998 3.0 95.7 290
11/5/1998 2.8 97.0 10
12/15/1998 6.7 54.1 10
1/19/1999 18.0 16.0 10
3/17/1999 8.1 42.6 6000
7/27/1999 3.7 87.8 64
8/31/1999 8.0 43.7 310
9/30/1999 89.0 3.1 6000
10/28/1999 6.5 56.1 210
11/23/1999 5.8 62.0
12/28/1999 5.8 62.0 100
2/23/2000 8.7 39.2 3300
3/30/2000 8.4 41.0 2100
4/26/2000 9.1 36.7 20000
5/30/2000 8.3 41.0 2000
6/28/2000 14.0 22.1 130
a Flow adjusted from USGS East Fork Deep River Gage 02099000

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Table 12. NCDENR Special Study Monitoring Data for Richland Creek and Muddy Creek (2003)
Date
Flow
(cfs) a
Flow
Regime (%)
Baker Road
(#/100 mL)
Road
(#/100 mL)
Riverdale
Road
(#/100 mL)
SR 1936
(#/100 mL)
Weant Road
(#/100 mL)
5/20/2003 19 14.8 420 560 140 900 930
5/27/2003 24 11.5 1200 1100 880 1000 2000
5/29/2003 16 18.5 420 220 150 440 900
6/3/2003 86 3.2 600 180 80 290 310
6/5/2003 29 9.2 4300 1900 2600 4000 2000
6/10/2003 25 10.9 390 240 160 770 340
6/17/2003 21 13.2 1300 540 320 2000 870
6/19/2003 16 18.5 5500 1200 1600 1800 1900
6/24/2003 9.9 33.2 340 1600 130 300 1100
7/1/2003 8.4 41.0 570 2400 340 3000 2300
7/2/2003 81 3.4 6000 6000 6000 6000 6000
a Flow adjusted from USGS East Fork Deep River Gage 02099000
Table 13. UCFRBA Monitoring Data for Richland Creek and Muddy Creek (2000-2003)
Date Flow (cfs) a
Flow Regime
(%)
Baker Road
(#/100 mL)
Cedar Square
Road (#/100 mL)
4/27/2000 8.00 0.44 5600 160
5/5/2000 7.00 0.52 290 110
6/6/2000 13.00 0.24 5000 2200
7/7/2000 5.50 0.66 19000 840
8/3/2000 8.30 0.41 6000 5800
9/7/2000 11.00 0.30 460 530
10/11/2000 6.40 0.56 240 660
11/21/2000 5.60 0.65 1000 1080
12/6/2000 6.10 0.60 42 44
1/18/2001 16.00 0.19 1990 740
2/16/2001 21.00 0.13 1820 820
3/15/2001 68.00 0.04 4600 195
4/6/2001 16.00 0.19 74 140
5/11/2001 9.10 0.37 730 240
6/15/2001 8.10 0.43 5600 3200
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Date Flow (cfs) a
Flow Regime
(%)
Baker Road
(#/100 mL)
Cedar Square
Road (#/100 mL)
7/2/2001 5.80 0.62 770 960
8/2/2001 8.70 0.39 534 120
9/4/2001 19.00 0.15 520 2
10/3/2001 4.80 0.73 800 1400
11/2/2001 3.70 0.88 114 40
12/14/2001 6.00 0.61 2200 520
1/4/2002 8.80 0.38 103 83
2/6/2002 7.90 0.44 54 34
3/6/2002 6.20 0.59 34 17
4/3/2002 4.40 0.79 2 36
5/3/2002 7.40 0.47 960 100
6/4/2002 3.40 0.91 500 460
7/2/2002 6.90 0.52 12000 4200
8/7/2002 0.64 1.00 1700 1060
9/3/2002 8.50 0.41 400 500
10/3/2002 2.20 0.99 12000 600
11/8/2002 13.00 0.24 245
11/15/2002 14.00 0.22 1080
12/10/2002 17.00 0.17 255 800
1/7/2003 10.00 0.33 74 115
2/5/2003 17.00 0.17 110 680
3/11/2003 13.00 0.24 400 95
4/14/2003 24.00 0.12 640 280
5/8/2003 16.00 0.19 295 640
6/5/2003 29.00 0.09 8400 5600
a Flow adjusted from USGS East Fork Deep River Gage 02099000
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APPENDIX B LOAD REDUCTION CALCULATIONS
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Table 14. Richland Creek at Riverdale Road: Estimation of Load Reduction (#/day)
Based on Fecal Coliform Instantaneous Standard
Flow
Interval Target Load Existing Load
37 8.74E+10 1.14E+11
41 8.06E+10 9.18E+10
42.6 7.87E+10 1.31E+12
39.2 8.45E+10 7.75E+11
40.6 8.16E+10 4.76E+11
36.7 8.84E+10 4.91E+12
41 8.06E+10 4.48E+11
10.9 2.33E+11 5.70E+11
18.5 1.55E+11 6.91E+11
Geomean 9.99E+10 5.47E+11

Table 15. Richland Creek at Riverdale Road: Estimation of Load Reduction (#/day)
Based on Fecal Coliform Geometric Mean Standard
Flow
Interval Target Load Existing Load
13.2 9.80E+10 2.66E+11
17.1 7.80E+10 1.41E+11
Geomean 8.75E+10 1.93E+11

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Table 16. Muddy Creek at Muddy Creek Road: Estimation of Load Reduction (#/day)
Based on Fecal Coliform Instantaneous Standard
Flow Interval Target Load Existing Load
14.1 1.66E+11 2.58E+11
11.5 2.10E+11 6.41E+11
12.6 1.84E+11 2.75E+11
18.5 1.40E+11 4.66E+11
33.2 8.66E+10 3.85E+11
40.6 7.35E+10 4.90E+11
Geomean 1.34E+11 3.99E+11

Table 17. Muddy Creek at Muddy Creek Road: Estimation of Load Reduction (#/day)
Based on Fecal Coliform Geometric Mean Standard
Flow
Interval Target Load Existing Load
13.2 8.82E+10 4.22E+11
17.1 7.02E+10 3.52E+11
Geomean 7.87E+10 3.85E+11

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Table 18. Estimates of Fecal Coliform Loading Rates for Urban and Rural Lands
Landuse Type FC Conc.
(mg/L)1
Mixed forest/pasture/ low density
residential
15
Mixed forest, pasture, medium-
and low-density residential
20
Mixed forest, pasture, medium-
and low-density residential
24.5
Average Rural 19.8
Industrial 27.5
Industrial 14.6
Medium-density residential 29
Medium-density residential 26.5
High-density residential 15
Developing 13
Average Urban 20.9
Source: USGS 1999
1 Loading estimates not developed by USGS for coliform

Table 19. Estimates of Direct Fecal Coliform Contribution from Urban Sources
Typical SSO and Sewer
Effluent Concentration
(#/100mL)
Estimated Percent of Storm
Event Contribution
Additional Contribution to
Urban Fecal Loading Rate
(#/100mL)
10,0001 0.2562 25.6
1 Source: (EPA, 2001)
2 Based on reported SSO overflows

Table 20. Relative Urban and Rural Fecal Coliform Areal Loading for Richland Creek
Landuse Landuse Distribution Relative FC Rate FC Loading Ratio
Rural (non-MS4) 50.5% 19.8 29.9%
Urban (MS4) 49.5% 46.5 70.1%

Note: Fecal coliform data collected at nine urban and rural sites were analyzed to estimate average fecal coliform
concentrations in stormwater runoff. The urban rate estimate was increased based on available SSO and sewer
break monitoring and literature to represent the non-runoff associated contributions. The relative percent
contributions of fecal coliform were multiplied by the landuse distribution and normalized to estimate the relative
loading ratio for urban (MS4) and rural (non MS4) areas.
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Table 21. Relative Urban and Rural Fecal Coliform Areal Loading for Muddy Creek
Landuse
Landuse
Distribution Relative FC Rate FC Loading Ratio
Rural (non-MS4) 28.2% 19.8 64.3%
Rural (in MS4 area) 32.3% 19.8 Combined with Rural
(non-MS4)
contribution
Urban (not in MS4 area) 4.9% 46.5 Combined with Rural
(non-MS4)
contribution
Urban (MS4) 34.6% 46.5 35.7%

Note: Fecal coliform data collected at nine urban and rural sites were analyzed to estimate average fecal coliform
concentrations in stormwater runoff. The relative percent contributions of fecal coliform were multiplied by the
landuse distribution and normalized to estimate the relative loading ratio for urban (MS4) and rural (non MS4)
areas.
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APPENDIX C AFFIDAVITS OF PUBLICATION FOR PUBLIC NOTICE

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