NONPOINT SOIREE SICCESS STOIY
Controlling Nonpoint Source Pollution from Agricultural Areas
Restores Abbott s Mill Pond
Waterbody Improved
Runoff from agricultural and residential areas caused high
bacteria levels in Delaware's Abbott's Mill Pond. As a result, the
Delaware Department of Natural Resources and Environmental Control (DNREC) added the pond
to the 1998 Clean Water Act (CWA) section 303(d) list of impaired waters for bacteria. Watershed
stakeholders provided technical assistance and installed agricultural best management practices
(BMPs) in the pond's watershed, causing bacteria levels to decline. As a result, DNREC removed
Abbott's Mill Pond from the state's 2006 list of impaired waters for bacteria.
Problem
Abbott's Mill Pond was created more than 200 years
ago when Johnson Branch was dammed to provide
power to a grist mill. Today, the pond covers approxi-
mately 25 acres on Johnson Branch, which is a tribu-
tary near the headwaters of Delaware's 76-square-mile
Mispillion River watershed. The mill pond is now part
of the Abbott's Mill Nature Center, which maintains the
pond and the restored mill for public education and
recreation purposes.
The 20-mile-long Mispillion River meanders through
farmlands and wetlands in southeastern Kent County
and northeastern Sussex County, and eventually
flows into Delaware Bay (Figure 1). Although the
upper watershed drains mostly agricultural lands and
wetlands, it includes two urban areas: Milford and
Houston.
Primary sources of nonpoint source pollution in the
watershed likely include runoff from agricultural activi-
ties (e.g., fertilizer and manure application), concen-
trated areas of animal production and failing septic
systems.
Monitoring data collected in the late 1990s indicated
that Abbott's Mill Pond failed to meet the state's
enterococcus bacteria numeric criterion, which
requires that the annual geometric mean be less than
100 colony-forming units (cfu) per 100 milliliters (ml).
The pond did not support its freshwater primary
contact designated use, prompting the state to add
the pond to Delaware's 1998 CWA section 303(d) list
of impaired waters for bacteria.
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Watershed
Chesapeake Bay
Inland Bay
Piedmont Bay
Delaware Bay
0 0.5 1 2 Miles
Figure 1. Abbott's Mill Pond is in the Upper Mispillion
River watershed in central Delaware.
In 2006 the U.S. Environmental Protection Agency
developed a total maximum daily load (TMDL) to
address the nutrients and bacteria loading throughout
the Mispillion River watershed, which includes Abbott's
Mill Pond. To achieve TMDL targets and meet water
quality standards in the pond, the TMDL required a
57 percent reduction in nitrogen and phosphorus load-
ings and an 87 percent reduction in bacteria loadings
from the surrounding watershed.
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Project Highlights
The Sussex and Kent County conservation districts
(SCO and KCD, respectively) offered technical
assistance to the farming community by provid-
ing nutrient management planning and cost-share
funding for agricultural BMPs. The conservation
districts also partnered with the U.S. Department of
Agriculture's (USDA's) Natural Resources Conservation
Service (NRCS) to develop conservation plans and
Environmental Quality Incentive Program (EQIP)
contracts. Between 2002 and 2014, watershed
partners worked with landowners to enroll an aver-
age of 1,400 acres of cover crop per year and imple-
ment nutrient management plans on approximately
100 percent of available lands.
In addition, several BMPs were installed on poultry
operations within the watershed, including 13 manure
storage structures, 11 composters, and 25 heavy use
protection areas. The SCO and KCD Planners continue
to work with farmers throughout the watershed, pro-
viding ongoing technical assistance to ensure improved
water quality.
Delaware's USDA Conservation Reserve Enhancement
Program (CREP) was established in 1999 to protect
and enhance environmentally sensitive land and
waters in the coastal plain geographic areas of the
Delaware, Chesapeake and Inland Bays watersheds
by establishing voluntary land retirement agreements
with agricultural producers. To assist in CREP program
development and implementation, in 1999 Delaware's
Nonpoint Source Program committed CWA section
319 funds to create a full-time Delaware CREP Program
Coordinator position. Between 1999 and 2014, the
CREP Program Coordinator helped install 4.9 acres of
wildlife plantings, 15 acres of grass buffers, 3.5 acres of
wetland restoration, and 187 acres of hardwood trees
in the Abbott's Mill Pond watershed.
Figure 2. Abbott's Mill Pond water quality has
improved, thanks to restoration efforts.
Results
Bacteria levels in the pond have decreased in response
to the more than 10 years of water quality protec-
tion and restoration efforts in the Mispillion River
watershed (Figure 2). DNREC collected monitoring
data at two stations in Abbott's Mill Pond between
September 2000 and August 2005. In one station,
the geometric mean of the 22 samples collected over
the 5-year period was 50 cfu/100 ml. In the other
station, 16 samples showed a geometric mean of
53 cfu/lOOml. Since both were well below Delaware's
fresh water bacteria water quality standard of
100 cfu/100 ml, DNREC removed the 25-acre Abbott's
Mill Pond (DE-210-L06) from the state's list of impaired
waters in 2006.
Partners and Funding
Key partners included KCD, SCO, NRCS and the
Delaware Nonpoint Source Program. Approximately
$1.5 million in federal CWA section 319 funds support-
ed the costs of the Abbott's Mill Pond subwatershed
restoration effort. Additional funding came from
the USDA (through EQIP and CREP) and Delaware's
Conservation Cost Share Program (which was provided
through KCD and SCO). Because of the nature of the
funding and enrollment procedures, much of the
funding provided by watershed partners has been
immeasurable.
yss
Ill
o
U.S. Environmental Protection Agency
Office of Water
Washington, DC
EPA841-F-16-001D
February 2016
For additional information contact:
Mark Hogan, Planner
Delaware Department of Natural Resources
and Environmental Control
Mark. Hogan@state.de.us
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