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Watershed Project Leads to Cleaner Water in Smith Swamp
Waterbody Improved NonPoint source (NPS) pollution from agriculture runoff and failing
septic systems has contributed to elevated bacteria levels in the
Smith Swamp watershed. Specifically, Smith Swamp failed to attain its primary recreation designated
use, prompting South Carolina to add this waterbody to the 1998 Clean Water Act (CWA) section
303(d) list of impaired waters for bacteria impairment. A total maximum daily load (TMDL) for fecal
coliform (FC) was developed for Smith Swamp in 2005 based on exceedances of bacteria water
quality standards (WQS) at a key monitoring station in this watershed. In response, stakeholders
conducted outreach to the public, implemented agricultural best management practices (BMPs),
and repaired failing septic tanks. Water quality in the watershed has since significantly improved,
and this key monitoring station is now designated as fully supporting.
Problem
The Smith Swamp watershed covers an area of roughly
23,350 acres in Marion County (Figure 1). The water-
shed captured by water quality monitoring station
PD-187 contains 1,645 acres and drains the southeast
portion of the town of Marion. The area is mostly
agricultural, but roughly 26 percent is developed.
There are large numbers of cattle farms, confined hog
operations, horse "hobby" farms, and crop farms that
apply hog manure and poultry litter to the land. Most
rural homes and businesses in the area rely on septic
tanks for wastewater treatment.
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 (ml_). Through extensive monitoring
by the South Carolina Department of Health and
Environmental Control (SCDHEC) at station PD-187
in the Smith Swamp watershed (see Figure 1), recre-
ational uses were found to be only partially supported
due to the bacteria exceedances, leading SCDHEC
to place PD-187 on the CWA section 303(d) list of
impaired waters in 1998.
SCDHEC also developed a TMDL for FC bacteria at sta-
tion PD-187 in 2005. The TMDL said it was necessary
to meet a target of 9.20E+10 CFU/day, or to have a 66
percent reduction to achieve the water quality target.
Smith Swamp Watershed
PO-187
Figure 1. The Smith Swamp watershed in eastern South
Carolina has shown water quality improvement at SCDHEC
monitoring station PD-187.

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Story Highlights
Smith Swamp Bacteria Data (2004-2018)
In 2008, the Pee Dee Resource Conservation &
Development Council (RC&D) began an effort to repair
septic tanks and implement agricultural best manage-
ment practices (BMPs)—specifically targeting swine,
cattle, and horse farms—as part of the Little Pee Dee
River Watershed Water Quality Improvement Project
covering the entire Little Pee Dee River and Catfish
Creek watersheds.
Clemson University's Confined Animal Manure
Managers Program team partnered on the project,
conducting two seminars during this project for 35
local swine producers. As a result, six swine farms
developed conservation plans and implemented
BMPs to better manage the application of wastewater
on their farms. To reach cattle farmers, the project
team contacted the Cattlemen's Association and local
agricultural stores and used doorknob handouts, flyers
in stores, and word of mouth between neighbors.
Consequently, 18 cattle farms received individualized
conservation plans and, as a total, implemented the
following BMPs on their properties: 484 acres of runoff
management; 25 acres of critical area stabilization;
and 77,265 feet of stream bank stabilization, sensitive
area protection, and cross-fencing. Partners also
worked with landowners to start prescribed grazing
with their livestock, affecting 484 acres, and to exclude
herds from waterways and provide alternative water
sources. In total, landowners installed 12 wells and 39
troughs along with 36,089 square feet of heavy use
areas to reduce FC runoff. Hobby farms are typically
excluded from the U.S. Department of Agriculture's
(USDA's) Environmental Quality Incentives Program
cost-share availability, providing a unique opportunity
for CWA section 319 funding to address NPS pollution
from these farms. Thus, this project supported two
workshops for hobby farmers, educating over 48 horse
farmers and allowing for implementation of conserva-
tion plans to assist historically underserved horse
producers in protecting their water quality.
A local community leader was hired to lead septic tank
outreach and implementation, as past experience
showed that a well-known community member would
build trust more quickly. As a mark of success, the
project team located and repaired or replaced 108
failing septic tanks compared to the estimated 60 that
were thought to have issues upstream of the drinking
water intake. Horry Soil and Water Conservation
-	Partially Supported
-	Fully Supported
2004	2006
2010	2012
303(d) Assessment
Figure 2. Percent exceedance of the bacteria single sample
maximum standard at Station PD-187.
District (SWCD) continues to address water quality
issues in the Pee Dee through outreach and education,
agricultural BMPs, and septic repair and replacement.
Results
A comparison of data collected at station PD-187
before the project began in 2008 and after its comple-
tion in 2011 indicates that the site improved from not
supporting, to partially supporting, and finally to fully
supporting recreational use at this monitoring site
(Figure 2). Bacteria levels have consistently met WQS
at station PD-187 since 2008. As a result, Smith Swamp
was removed from the list of impaired waters for
FC in 2014. In total, implementation efforts reduced
pollutant loadings of nitrogen by 24,285 pounds/year,
phosphorus by 6,443 pounds/year, and FC bacteria by
1.497E+14 CFU.
Partners and Funding
Pee Dee RC&D encouraged project participation using
partnerships with Santee-Wateree RC&D; the Marion
County and Dillon County SWCDs; the USDA Natural
Resources Conservation Service in Marion, Dillon, and
Horry counties; South Carolina Department of Natural
Resources; Clemson University Cooperative Extension
Service; and local landowners. These partners
provided $511,376 in cash and in-kind services. CWA
section 319 funding from SCDHEC also provided
$693,490. Overall, with the assistance of partners and
landowners, this project contributed $696,490 directly
in cost-share funds to 843 people and provided
information on BMPs to over 2,000 people to help
reduce NPS pollution.
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U.S. Environmental Protection Agency
Office of Water
Washington, DC
EPA 841-F-19-001HH
November 2019
For additional information contact:
Carmony A Corley
South Carolina Department of Health and
Environmental Control, Bureau of Water
803-898-4401 • corleycl@dhec.sc.gov

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