NONPOINT SOURCE SUCCESS STORY
Septic System Repairs Improve Water Quality in Horse Creek
Waterbody Improved
Septic leachate from failing onsite septic systems resulted in
high pathogen levels in Horse Creek. As a result, South Carolina
added the creek to its 1998 Clean Water Act (CWA) section 303(d) list for fecal coliform (FC) bacteria
impairment and failure to attain its primary recreation designated use. After the 1998 listing, watershed
outreach and septic repairs were conducted which decreased bacteria loading to the creek. As a result,
water quality improved, allowing South Carolina to remove Horse Creek from its impaired waters list for
FC bacteria in 2008.
Problem
The 103,463-acre Horse Creek watershed is part of the
Middle Savannah River watershed and is a tributary of
the Savannah River downstream of Lake Thurmond. It
is in Aiken and Edgefield counties and drains portions
of the cities of Aiken and North Augusta (Figure 1).
Primary land uses include forest (45 percent), agricul-
ture (26 percent) and urban (19 percent). Growth is
predominantly residential with development of numer-
ous subdivisions and commercial centers.
The South Carolina Department of Health and
Environmental Control (SCDHEC) monitored FC bacte-
ria at several stations in the Horse Creek watershed.
State criteria for FC impairment require that no more
than 10 percent of the total samples during any 30-day
period exceed 400 colony-forming units (CFU) per 100
milliliters. FC bacteria data collected from 1998-2002
were assessed to determine impairment of standards
for recreational use due to FC bacteria. Approximately
13 percent of samples violated standards; as a result,
SCDHEC placed Horse Creek (SV-072) on the CWA
section 303(d) list of impaired waters in 1998. A total
maximum daily load (TMDL) for FC bacteria was devel-
oped in 2005.
Project Highlights
Partners implemented a septic system repair effort in
the Horse Creek watershed from April 2007 to October
2009. As a preliminary step, the city of North Augusta
and Aiken County helped to assess and interpret the
results of an aerial infrared thermographic survey
conducted in the early spring of 2007 to identify tem-
perature changes that could indicate leaking or failing
septic systems. In the initial project phase, partners
worked on 65 septic systems, pumping out systems
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SV-072 Criteria Exceedance (%)
I I 1998 13%
I | 2002 24%
^| 2006 67%
^| 2008 0%
I I 2014 4%
SCSV-072_S_06
Figure 1. Horse Creek is in south-central South
Carolina. Data show the percent exceedances of FC
bacteria criteria at station SV-072 over time.
and replacing septic tanks, failed drain fields, and
entire antiquated systems that no longer functioned
(Figure 2). In the second project phase, additional
funding allowed another 30 systems to be repaired, for
a total of 95 systems.
Publicity for the septic system repair project included
developing and distributing a brochure, sending letters
directly to septic system contractors, and publishing
articles in the Aiken Standard and the city of North
Augusta's stormwater publication, The Resource.
Not all systems could be repaired. For example, the
aerial infrared thermographic survey showed evidence
of an illicit discharge at one residence (Figure 3). All
sewage was being dumped from a pipe directly into
Horse Creek, which then flowed into Langley Pond, a
recreational swimming site. Upon talking to the home-
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Figure 2. This Horse Creek watershed septic system
had failed due to a cave-in.
Figure 3. An aerial infrared thermogeographic survey
picture shows an illicit discharge at point 40B.
owner, it was discovered that the septic system had
never worked because of its location in a saturated
floodplain. Five other houses had septic systems in
the same floodplain area, which posed a similar failure
risk. SCDHEC granted an extension to allow the project
partners to find a solution. In August 2009 these
homes were connected to the municipal sewer service.
Clients completed questionnaires both before and
after repairs were made to assess their knowledge of
environmental and health risks associated with septic
system failures. Results showed that participating in
the project led to an increase in clients' overall knowl-
edge about how to care for septic systems.
Additionally, an Enviroscape Model was purchased
with funds from a CWA section 319 grant and used
to teach about watersheds and point source and
nonpoint source pollution. The science coordinator in
Aiken County taught the program in middle schools,
while members of the Aiken County Master Gardener
Association were trained to share the program with
garden clubs and other civic organizations (approxi-
mately 500 adults participated in the programs).
Results
Monitoring of the impaired segment continued dur-
ing and afterTMDL implementation. Results show
monitoring site SV-072 met water quality standards
and achieved full support for contact recreation in
the 2008 CWA section 303(d) assessment (Figure 4).
In total, implementation efforts reduced pollutant
loadings of nitrogen by 1119.6 pounds, phosphorus
by 439.2 pounds, and FC bacteria by 8.70E+11 CFU. Of
note, in 2009 SCDHEC added monitoring site SV-072 to
a special study which allowed for weekly sampling for
FC bacteria throughout the entire year. This increased
sampling allowed for more temporal data collection
which found the site to be meeting state standards.
Partners and Funding
Multiple parties collaborated to restore Horse Creek,
including SCDHEC, Clemson University, the Aiken
Natural Resources Conservation Service (NRCS) offices,
the city of North Augusta, Aiken County, the U.S.
Environmental Protection Agency and local landown-
ers. A CWA section 319 grant provided $247,779 to
support project oversight. Clemson University, the
Aiken NRCS offices, the city of North Augusta, and
Aiken County contributed in-kind services worth a
combined $64,288 to support TMDL implementation,
project management, and participant recruitment.
Lastly, landowners provided $101,247 through cash
and in-kind services for best management practice
cost-share.
Horse Creek Bacteria Data (1998-2014)
100%
9091
g 80%
§ 70%
g 60%
£ 50%
1r 40%
24%
67%
I
Not supported
13o/0 Partial Support
• ^^^9 ^^^8 d%
Not Impaired 0%
1998303(d) 2002303(d) 2006303(d) 2008303(d) 2014303(d)
Assessment Assessment Assessment Assessment Assessment
Figure 4. FC bacteria levels met water quality standards at
station SV-072 in 2008 and 2104.
K1
Ill
o
U.S. Environmental Protection Agency
Office of Water
Washington, DC
EPA841-F-16-001M
August 2016
For additional information contact:
Scott Hagins, Nonpoint Source Coordinator
SCDHEC-Bureau of Water
Water Quality Division
803-898-1584 • haginsms@dhec.sc.gov
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