HomeMy WebLinkAboutSec B Ch 5 03-08-34
Section B - Chapter 5
Catawba River Subbasin 03-08-34
Irwin Creek, Long Creek, McAlpine Creek and Sugar Creek
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5.1 Subbasin Overview
This subbasin is in the Southern Outer Piedmont
ecoregion and contains the Sugar Creek watershed, a
portion of Lake Wylie, and much of the City of Charlotte
metropolitan area. This is the most heavily urbanized
region of the basin and the state, and its population is
expected to increase over 30 percent by 2020 (Table A-
6). Only 52 percent of the subbasin is forested – the
smallest percentage of any of the subbasins.
There are currently over 50 NPDES permitted
dischargers in this subbasin. The largest one is the
Charlotte/Mecklenburg Utilities District, which
discharges to Irwin Creek (15 MGD), McAlpine Creek
(64 MGD), and Little Sugar Creek (20 MGD).
There are 30 facilities in this subbasin required to
monitor effluent toxicity. Of these, six facilities have
had more than one failing toxicity test since 1997:
American Truetzschler, Inc. (12), Cousins Real
Estate/Gateway Village (12), Duke Power/Allen 002 (3),
First Union Commons (4), Hoechst Celanese/Dreyfus
(2), and Unocal/Rhom and Haas Facility (5). Four other
facilities had one failing test since 1997: (AquAir
WWTP, Belmont WWTP, CMUD/Irwin Creek WWTP,
and CMUD/McAlpine Creek WWTP).
Subbasin 03-08-34 at a Glance
Land and Water Area
Total area: 324 mi2
Land area: 317 mi2
Water area: 7mi2
Population Statistics
2000 Est. Pop.: 408,821 people
Pop. Density:1,231 persons/mi2
Land Cover (percent)
Forest/Wetland: 52%
Surface Water: 2%
Urban: 32%
Agriculture: 13%
Counties
Gaston and Mecklenburg
Municipalities
Belmont, Charlotte, Huntersville,
Matthews, Mint Hill, Mount Holly
and Pineville
There were eight benthic macroinvertebrate community samples and four fish community
samples (Figure B-5 and Table B-9) collected during this assessment period. One site improved;
three sites remained the same; two sites had a lower bioclassification, and two sites were
sampled for the first time during this assessment period. There are ten ambient monitoring
stations located in this subbasin, both in North and South Carolina.
Based upon benthic macroinvertebrate data, McAlpine Creek and Sugar Creek (at SC 160) were
given Fair bioclassifications in 1997 and 2002, while Sugar Creek at SR 1156 and Little Sugar
Creek were given Poor bioclassifications. Both streams had been given Fair bioclassifications in
1997. These low bioclassifications are due to urban runoff, poor habitat, and may be influenced
by wastewater discharges. The declines were attributed to the drought rather than significant
declines in water quality.
Section B: Chapter 5 - Catawba River Subbasin 03-08-34 146
Table B-9 DWQ Assessment and Use Support Ratings Summary for Monitored Waters in Subbasin 03-08-34
Biological Ambient Other 2004 1998
CATAWBA RIVER
(Lake Wylie below
elevation 570)11-(122) WS-IV & B CA 601.1 ac.AL
C3900000 nce
C4220000 nce L-1 ce I FS
CATAWBA RIVER
(Lake Wylie below elevation
570) North Carolina portion 11-(123.5) WS-V & B 3,418.5 ac.AL
C7000000 nce
C7400000 nce
C7500000 nce L-1 ce I FS
Irwin Creek 11-137-1 C 11.8 mi.AL
B-2 F--97
B-2 P--02
SF-2 P--97
SF-2 P--02 C8896500 nce IPS
Little Sugar Creek 11-137-8b C 5.5 mi.AL
B-3 F--97
B-3 P--02
SF-1 F--97
SF-1 GF--02 C9210000 nce IPS
Long Creek 11-120-(2.5) WS-IV 11.3 mi.AL C4040000 ce IPS
McAlpine Creek
(Waverly Lake)11-137-9a C 8.5 mi.AL C9370000 nce NR PS
McAlpine Creek
(Waverly Lake)11-137-9c 4.6 mi.AL
B-4 F--97
B-4 F--02 IPS
Sugar Creek 11-137a C 0.3 mi.AL
B-1 F--97
B-1 F--02 C8896500 nce IPS
Sugar Creek 11-137b 10.9 mi.AL C9050000 nce NR PS
CATAWBA RIVER
(Lake Wylie below
elevation 570)11-(122) WS-IV & B CA 601.1 ac.REC C4220000 nce S
CATAWBA RIVER
(Lake Wylie below elevation
570) North Carolina portion 11-(123.5) WS-V & B 3,418.5 ac.REC C3900000 nce S-
Irwin Creek 11-137-1 C 11.8 mi.REC C8896500 ce NR -
Little Sugar Creek 11-137-8b C 5.5 mi.REC C9210000 ce NR -
Long Creek 11-120-(2.5) WS-IV 11.3 mi.REC C4040000 ce NR -
Data Type with Map Number
and Data Results
Use Support Rating
Category
Assessment Unit
Number DWQ Classification Length / AreaWaterbody
Section B: Chapter 5 - Catawba River Subbasin 03-08-34 148
Table B-9 DWQ Assessment and Use Support Ratings Summary for Monitored Waters in Subbasin 03-08-34
Biological Ambient Other 2004 1998
Data Type with Map Number
and Data Results
Use Support Rating
Category
Assessment Unit
Number DWQ Classification Length / AreaWaterbody
McAlpine Creek
(Waverly Lake)11-137-9a C 8.5 mi.REC C9370000 ce NR -
Sugar Creek 11-137a C 0.3 mi.REC C8896500 ce NR -
Sugar Creek 11-137b C 10.9 mi.REC C9050000 ce NR -
Assessment Unit Number - Portion of DWQ Classified Index where monitoring is applied to assign a use support rating.
Use Categories:Monitoring data type: Use Support Ratings 2004:
AL - Aquatic Life F - Fish Community Survey E - Excellent S - Supporting, I - Impaired, NR - Not Rated
REC - Recreation B - Benthic Community Survey G - Good
SF - Special Fish Community Study GF - Good-Fair Use Support Ratings 1998:
L - Lakes Assessment F - Fair FS - fully supporting
P - Poor PS - partially supporting, NS - not supporting
nce - no criteria exceeded
ce - criteria exceeded
Ambient Data
Bioclassifcations:
Section B: Chapter 5 - Catawba River Subbasin 03-08-34 149
ambient monitoring stations as well. Refer to 2003 Catawba River Basinwide Assessment Report
at http://www.esb.enr.state.nc.us/bar.html and Section A, Chapter 3 for more information on
monitoring.
Waters in Part 5.3 are identified by assessment unit number (AU#). This number is used to track
defined segments in the water quality assessment database, 303(d) Impaired waters list, and the
various tables in this basin plan. The assessment unit number is a subset of the DWQ index
number (classification identification number). A letter attached to the end of the AU# indicates
that the assessment is smaller than the DWQ index segment. No letter indicates that the
assessment unit and the DWQ index segment are the same.
Use support ratings are summarized in Part 5.2 below. Recommendations, current status and
future recommendations for waters that were Impaired in 1999 and newly Impaired waters are
discussed in Part 5.3 below. Water quality issues related to the entire subbasin are discussed in
Part 5.4. Refer to Appendix III for use support methods and more information on all monitored
waters.
5.2 Use Support Assessment Summary
Use support ratings in subbasin 03-08-34 were assigned for aquatic life, fish consumption,
recreation and water supply. All water supply waters are Supporting on an Evaluated basis based
on reports from DEH regional water treatment plant consultants. Refer to Table B-10 for a
summary of use support ratings by use support category for waters in the subbasin.
Section B: Chapter 5 – Catawba River Subbasin 03-08-34 150
Table B-10 Summary of Use Support Ratings by Use Support Category in Subbasin 03-08-34
Life
Use Support
Rating
Aquatic Fish
Consumption Recreation Water
Supply
Monitored Waters
Supporting 0 0 4,019.6 ac 0
Impaired 39.5 mi
4,019.6 ac.00 0
Not Rated 35.2 mi 48.3 mi 0 0
Total 74.8 mi
4,019.6 ac
48.3 mi 004,019.6 ac
Unmonitored Waters
Supporting 0 0 0 30.4 mi
4,019.6 ac
Impaired 0 246.8 mi
4,019.6 ac 0 0
Not Rated 93.2 mi 1.0 mi 0 0
No Data 79.8 mi 0 199.5 mi. 0
Total 173.0 mi 247.8 mi
4,019.6 ac
199.5 mi
4,019.6 ac
30.4 mi
4,019.6 ac
Totals
All Waters 247.8 mi
4,019.6 ac
247.8 mi
4,019.6 ac
247.8 mi
4,019.6 ac
30.4 mi
4,019.6 ac
Note: All waters include monitored, evaluated and waters that were not assessed.
5.3 Status and Recommendations of Previously and Newly Impaired
Waters
The following waters were identified in the 1999 basin plan as Impaired or are newly Impaired
based on recent data. The current status and recommendations for addressing these waters are
presented below. These waters are identified by assessment unit number (AU#). Refer to the
overview above for more information on AUs.
5.3.1 The Sugar Creek Watershed Including:
Irwin Creek [AU# 11-137-1]
Little Sugar Creek [AU# 11-137-8]
McAlpine Creek [AU# 11-137-9a and 11-137-9c]
Sugar Creek [AU# 11-137a and 11-137b]
1999 Recommendations
These four streams and their smaller tributaries collectively drain the metropolitan center of
Charlotte in Mecklenburg County. The watershed receives large amounts of both point and
nonpoint pollution from the urban areas, severely impacting stream health in each of the streams.
Similar habitat conditions are found at all sample sites within this watershed, sand/silt substrate,
Section B: Chapter 5 - Catawba River Subbasin 03-08-34 151
severe bank erosion, and disturbed or nonexistent riparian vegetation. Elevated levels of both
fecal coliform bacteria and turbidity indicate impairment by urban runoff and wastewater
discharges in all four streams. In the 1999 plan, DWQ noted they would work closely with
Mecklenburg County and the City of Charlotte during the development of a TMDL and
implementation plan for this watershed.
Current Status and 2004 Recommendations
Impairment for Sugar Creek = 11.2 mi.; Irwin Creek = 11.8 mi.; Little Sugar Creek = 5.5 mi.;
and McAlpine Creek = 4.6 mi.
Water quality in general has remained low but stable over the last planning cycle. In 2002,
declines were noted on Sugar Creek (B-2) and Little Sugar Creek (B-3), but this decline was
most likely due to the severe drought. The Irwin Creek site is showing a slight trend of lowered
conductivity since the middle 1990s. Conversely, McAlpine Creek at SR 3356 showed slightly
elevated conductivity trends since the middle 1990s. In addition, McAlpine Creek at SR 3356
had slightly elevated levels of NO monia since the early 1990s. Sugar Creek at
NC 51 has had slightly elevated levels in NO
notably since the early 1980s. Dissolved oxygen concentrations have steadily increased since the
late 1960s at this site. Sugar Creek at SC 160 has shown elevated trends in NO
dissolved oxygen since the late 1980s, while ammonia and total Kjeldahl nitrogen have
dramatically decreased since the late 1970s.
2 + NO3-N and am
2 + NO3-N, while other nutrients have decreased
2 + NO3-N and
Many streams in this watershed are also Impaired within South Carolina. Recreational or aquatic
life uses on Steele, Sugar and McAlpine Creeks are Impaired because of fecal coliform bacteria
or copper violations and appear on South Carolina’s Draft 2003 303(d) List (SCDEHC, 2002).
North Carolina is subject to an interstate TMDL developed by South Carolina and will therefore
cooperate on its development.
Fecal Coliform Bacteria TMDL
In response to a high level of government and citizen interest in a fecal coliform TMDL, a
stakeholder group was formed in 1999. The stakeholder group, lead by the Mecklenburg County
Department of Environmental Protection (MCDEP) and the DWQ, took a very active role in
every stage of the TMDL development process. MCDEP has a well-developed and respected
water quality management program and was able to take the lead role in both the source
assessment and model development.
The end result of this stakeholder effort was a comprehensive fecal coliform TMDL that received
approval in March 2002. The TMDL addresses all identifiable sources of fecal coliform
pollution including, but not limited to, wastewater treatment plants, sanitary sewer overflows,
stormwater runoff, failing septic systems, and background wildlife contributions. The TMDL
study indicated that excluding stormwater runoff, the primary contributors of fecal coliform
pollution in this watershed are point sources (WWTP, etc.) and direct input nonpoint sources
(failing septic systems). Table B-11 presents a summary of the TMDL and describes the
necessary reductions in fecal coliform contamination in the Sugar Creek watershed. Loading
reductions are defined for both point and nonpoint sources.
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Table B-11 Summary of Sugar Creek Watershed Fecal Coliform TMDL
Critical Conditions Site-specific critical conditions occurred during periods of low streamflow coinciding
with high fecal coliform loads from both the SSOs and the WWTPs.
Seasonality All seasons addressed.
Development Tools Watershed model, BASINS Versions
Supporting Documents Fecal Coliform Total Maximum Daily Load for the Irwin, McAlpine, Little Sugar and
Sugar Creek Watersheds, Mecklenburg County, and references listed in report.
TMDL(s) Waterbody TMDL (cfu/100ml)
Sugar Creek 8.4x1012
Irwin Creek 7.7x1012
Little Sugar Creek 9.4x1012
McAlpine Creek downstream of Sardis Road 1.1x1013
McAlpine Creek upstream of Sardis Road 6.8x1012
Loadings Sugar Creek watershed:
Point sources 7.4x10 /100ml (63% reduction)
Nonpoint sources 8.9x10 /100ml (58% reduction)
12 col11 col
Irwin Creek watershed:
Point sources 7.0x1012 col/100ml (60% reduction)
Nonpoint sources 7.3x1011 col/100ml (62% reduction)
Little Sugar Creek watershed:
Point sources 6.7x1012 col/100ml (43% reduction)
Nonpoint sources 2.6x1012 col/100ml (19% reduction)
McAlpine Creek watershed (downstream):
Point sources 7.8x1012 col/100ml (70% reduction)
Nonpoint Sources 3.2x1012 col/100ml (28% reduction)
McAlpine Creek watershed (upstream):
Point sources 7.8x1012 col/100ml (32% reduction)
Nonpoint sources 5.9x1011 col/100ml (68% reduction)
The MCDEP, Charlotte Mecklenburg Utilities, and Charlotte Mecklenburg Storm Water
Services can accomplish implementation of the TMDL cooperatively. Local coordination,
oversight and reporting for the TMDL should be the responsibility of the MCDEP. Each of the
three programs has currently funded efforts dedicated to reducing fecal coliform levels in
Charlotte’s streams, and these efforts can be augmented to fulfill the requirements of the TMDL
Implementation Strategy.
Phosphorus Load Reduction Strategy
In the summer of 2001, the South Carolina Department of Health and Environmental Control
(SCDHEC) filed a Petition for a Contested Case in the North Carolina Office of Administrative
Hearings regarding the renewal of the Charlotte Mecklenburg Utilities Department (CMUD)
McAlpine Creek wastewater treatment plant. The primary complaint on the part of SCDHEC
was that the permit was renewed without a phosphorus limit. Nearly all of South Carolina’s
municipal dischargers to the mainstem Catawba River (upstream of Lake Wateree) have been
given phosphorus limits, generally equivalent to 1 mg/l. The McAlpine Creek WWTP permit
had a phosphorus optimization study special condition that stipulated preparatory requirements
for the facility to ready itself for the upcoming phosphorus TMDL.
Section B: Chapter 5 - Catawba River Subbasin 03-08-34 153
In January 2002, SCDHEC, DWQ and CMUD reached an agreement on the terms of the
phosphorus limits at the McAlpine treatment plant and expanded the permitting strategy to
include the WWTPs on Sugar, Irwin and Twelvemile Creeks (in Union County). The final
settlement agreement includes four main points: phosphorus limits at all three CMUD facilities,
a bubble limit, a mass cap, and a TMDL. The phosphorus limit corresponds to 1 mg/l at the
permitted flows calculated on a 12-month rolling average. The bubble limit refers to a mass
limit for total phosphorus that applies to the combined discharge of all three CMUD plants. This
type of limit allows CMUD operational flexibility with regard to phosphorus removal. In order
to be protective of water quality in the downstream lakes, SCDHEC requested a maximum
combined limit to ensure optimized plant operation at all times. The maximum limit corresponds
to a concentration limit of 2 mg/l at maximum permitted flow. In addition, the agreement
includes a provision that will include DWQ and all affected NC entities in the TMDL process.
5.3.2 Long Creek [AU# 11-120-(2.5)]
Current Status and 2004 Recommendations
The Long Creek watershed drains north central Mecklenburg County between Charlotte and
Huntersville. Approximately 11.3 miles of Long Creek (from a point 0.6 mile downstream of
Mecklenburg County SR 2074 to a point 0.4 mile upstream of Mecklenburg County SR 1606)
are rated Impaired due to turbidity and exceedances of the manganese water quality standard.
Ambient data from the current assessment period indicate that the turbidity readings remain in
violation of the state standard. Fecal coliform concentrations are also above the state standard,
but Long Creek is not used for primary recreation. There are no NPDES discharges to this
stream, suggesting that impairment is likely a result of urban runoff, construction and agriculture
in the watershed. This evaluation is based on chemical monitoring data because DWQ does not
have biological monitoring locations on Long Creek at this time.
In 2002, Mecklenburg County entered into a partnership with the NCDOT and the NC Division
of Land Quality regarding the I-485 construction project through the Long Creek watershed.
NCDOT funded staff and resources for the development, monitoring and maintenance of 15
continuous automated monitoring sites located throughout the watershed, which automatically
download water quality data to a website every 15 minutes and alert staff regarding elevated
turbidity levels. In 2003 and 2004, the network detected several sedimentation problems that
were quickly corrected thus preventing significant downstream water quality impacts. The
program has been extremely successful and NCDWQ encourages similar programs and
partnerships when the opportunity arises in other watersheds.
Long Creek suffers from the impacts of rapid urbanization. Please refer to Section A, Chapter 4,
Part 4.13 for a detailed discussion on DWQ’s approach to and recommendations for this issue.
5.3.3 Lake Wylie [AU# 11-(122) and 11-(123.5)]
The area covered by Lake Wylie overlaps the boundaries of subbasins 03-08-34, 03-08-36 and
03-08-37. Therefore, a detailed discussion on Lake Wylie can be found in Section A, Chapter 4,
Part 4.7.3. Because of chlorophyll a standard violations, algal blooms, and dissolved oxygen
percent saturation values greater than 120 percent, Lake Wylie (4,019.6 acres, NC portion) is
Impaired by eutrophication. Data collected by the Mecklenburg County Water Quality Program
support these findings.
Section B: Chapter 5 - Catawba River Subbasin 03-08-34 154
5.4 Additional Water Quality Issues within Subbasin 03-08-34
Water Quality Threats to Streams in Urbanizing Watersheds
Subbasins in and around the Greater Charlotte Metropolitan Area are experiencing rapid growth
as new homes and businesses replace old farms and forests. This development places intense
pressure on the sensitive stream communities within those basins. In order to prevent aquatic
habitat degradation and Impaired biological communities, protection measures should be put in
place immediately. Refer to Section A, Chapter 4, Part 4.13 for a description of urban stream
water quality problems and recommendations for reducing impacts and restoring water quality.
Section B: Chapter 5 - Catawba River Subbasin 03-08-34 155