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NONPOINT SOURCE SUCCESS STORY

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Implementing Agriculture Management Practices Restored Iron Branch

Waterbody Improved

Runoff from agricultural areas caused high bacteria levels in
Delaware's Iron Branch of Indian River Bay. As a result, the
Delaware Department of Natural Resources and Environmental Control (DNREC) added the
watershed to the 1996 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 watershed, causing bacteria levels to improve. As a result, DNREC removed
Iron Branch from the state's list of impaired waters for bacteria in 2020.

Problem

iron Branch is a 23.15-square-mi!e watershed in the
indian River Bay watershed on the southeastern edge
of Deiaware in Sussex County (Figure 1). The Indian
River Bay watershed is one of three interconnected
watersheds that make up Delaware's inland Bays
(Rehoboth, Indian River and Little Assawoman bays).
Primary sources of nonpoint source pollution in the
watershed likely include runoff from agricultural
activities (e.g., fertilizer and manure application) and
concentrated areas of animal production.

Monitoring data collected indicated that Iron Branch
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) to support the freshwater
primary contact designated use. As a result, DNREC
added the Iron Branch watershed to Delaware's 1996
CWA section 303(d) list of impaired waters for bacte-
ria. Elevated nutrient levels also prompted the 1996
listing of Iron Branch as impaired due to nitrogen and
phosphorus.

In 1998, DNREC developed a total maximum daily
load (TMDL) to address nutrient loading throughout
the Inland Bays watersheds, which includes Iron
Branch. The TMDL stated that the nonpoint source
nitrogen and phosphorus loads from the upper Indian
River tributaries, which Include Iron Branch, shouid
be reduced by 85% and 65%, respectively. This was
expected to reduce nitrogen loads from 2,833 pounds
per day (lbs/day) to 425 ibs/day and phosphorous
loads from 84 ibs/day to 29 ibs/day. Reducing nutrient
sources should also reduce other nonpoint source
pollutants, such as pathogens.

Figure 1. Iron Branch is in southern Delaware.

Story Highlights

Delaware's U.S. Department of Agriculture's (USDA's)
Conservation Reserve Enhancement Program (CREP)
was established in '1999 to protect and enhance envi-
ronmentally 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 produc-
ers. 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.
The CREP Program Coordinator helped install 2 acres
of hardwood trees in the Iron Branch watershed.

The Sussex County Conservation District (SCD) offers
technical assistance to the farming community by pro-
viding nutrient management planning and cost-share

Major Basin
I—| Piedmont
I—| Delaware Bay
I—iChesapeake Bay

\
Indian River Bay


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funding for agricultural BMPs. The SCD also partners
with the USDA Natural Resources Conservation
Service (NRCS) to develop conservation plans and
Environmental Quality Incentive Program contracts.
Watershed partners worked with landowners to enroll
an average of 1.926 acres of cover crops and imple-
ment nutrient management plans on approximately
2,000 acres over 5 years (2015-2019).

Several BMPs were installed on operations within the
watershed, including 21 manure storage structures,
15 poultry carcass composters, 34 heavy use area
protection pads, among several other practices
available through NRCS. The manure relocation
program, In coordination with Delaware Department
of Agriculture, transferred 4,667 tons of manure
out of the watershed in 2015-2019. The SCD plan-
ners continue to work with farmers throughout the
watershed, providing ongoing technical assistance to
ensure improved water quality.

Results

Bacteria levels have decreased in response to the
more than 10 years of water quality protection and
restoration efforts in the Iron Branch watershed
(Figure 2). Data showed that the geomean levels were

362 cfu/100 m_ in 2012, 280 cfu/100 ml in 2014,
252 cfu/100 m_ in 2016, and 122.9 cfu/100 mL in 2018.
The geometric mean of 41 samples collected by DNREC
for 2020 at STORET Station 309041 (Iron Branch) was
95.8 cfu/100 mL. This is below Delaware's fresh water
bacteria water quality standard of 100 cfu/100 mL;
therefore, DNREC removed the 13.1-mile segment of
Iron Branch (DE-150-001-01) from the state's list of
impaired waters in 2020 per its Assessment and Listing
Methodology. Nutrient loads have also declined due to
the ongoing conservation work in the watershed, but
levels do not yet consistently meet standards.

Partners and Funding

Key partners included SCD, NRCS and the Delaware
Nonpoint Source Program. Between 2005 and 2020,
NRCS supported implementation efforts within the
watershed for $2.5 million. Over $321,000 in federal
CWA section 319 funds supported the costs of the
Iron Branch restoration effort. Because of the nature
of the funding and enrollment procedures, much of
the funding provided by watershed partners has been
extremely important, implementation efforts within
the watershed are continuing, thanks to the collabora-
tions and working relationships formed by the partners
and producers.

Figure 2. Iron Branch water quality is improving due to restoration and
pollution control activities.

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PROl*°

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U.S. Environmental Protection Agency
Office of Water
Washington, DC

EPA 841-F-21-001I
June 2021

For additional information contact:

Mark Hogan

Delaware Department of Natural Resources
and Environmental Control
302-739-9922 • Mark.Hogan@delaware.gov


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