Section 319
               NUNPUINT SUURCE PROGRAM  SUCCESS STORY
Implementing Best Management Practices Reduces Nitrogen in Two
Corsica River Tributaries
                  I            H
                  improved
                                  Algae blooms in the upper tidal reaches of Maryland's Corsica River
                                  prompted the Maryland Department of the Environment (MDE)
to add the river to the state's Clean Water Act (CWA) section 303(d) list of impaired waters in 1996 for
impairment of aquatic life and recreational use. MDE developed a total maximum daily load (TMDL) for
nitrogen and phosphorus. After six years of restoration efforts, water quality monitoring  in two nontidal
Corsica River tributaries shows a significant decrease in  nitrogen concentrations. These  improvements
indicate that  project partners are making progress toward meeting the Corsica River nutrient TMDL.


Problem
The six-mile-long Corsica River is a tidal tributary on
Maryland's Eastern Shore. It flows through Queen
Anne's County and the town of Centreville before
entering the Chester River, which discharges into
the Chesapeake Bay (Figure 1). Major land uses
in the 40-square-mile watershed are agriculture
(64 percent), woodland (28 percent) and developed
areas. The nontidal portions of the Corsica River are
designated for aquatic life protection and contact
recreation; most of the estuarine portions are desig-
nated as shellfish harvesting areas.

Algal blooms and other water quality problems in
the tidal portions of the Corsica River prompted
MDE to add this watershed assessment unit to the
CWA section 303(d) list in 1996 for impairment by
nutrients, suspended sediment and fecal coliform
bacteria. Water quality surveys conducted in 1997
found that the local eutrophication problems (the
overenrichment of aquatic systems caused by
excessive nutrient input) tended to be the greatest
slightly downstream of the tidal/nontidal interface.
Data showed chlorophyll a concentrations (a mea-
sure of algal content) as high as 146 micrograms
per liter (jug/L).

MDE developed a TMDL for nitrogen and phospho-
rus, which EPA  approved in 2000. According to the
TMDL, the major source of nutrient loading was
agricultural runoff (85 percent); other sources were
forest and urban nonpoint sources and the town of
Centreville's wastewater treatment plant (WWTP).
The TMDL established the following water quality
goals for the Corsica River: (1) chlorophyll a con-
centrations should remain below 50/jg/L,  and (2)
dissolved oxygen (DO) levels should remain above
the state's minimum water quality standard, 5 mil-
ligrams per liter (mg/L).
                                                                                     Corsica River
                                                                                      Watershed
                                               Legend
                                               Subwatersheds
                                               CZI Corsica Direct Drainage
                                               CZ1 Mill Stream Branch
                                               CH Three Bridges Branch and Gravel Run
                                               ^WRAS Project Area Boundary
                                                — Roads
                                               	Streams
                                              Figure 1. The Corsica River's three subwatersheds are part of the
                                              Corsica River Watershed Restoration Action Strategy (WRAS).
                                             Project Highlights
                                              In 1998 the Maryland General Assembly passed the
                                              Water Quality Improvement Act, which required that
                                              all agricultural operations with gross annual income
                                              over $2,500 and any livestock operations with more
                                              than eight animal units develop and implement nutri-
                                              ent management plans. All plans were developed by
                                              2004,  helping to reduce nutrient pollutant loading.

                                              In 2004 the town of Centreville, along with several
                                              key local partners and with support and cooperation
                                              from MDE and the Maryland Department of Natural

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       Resources (MDNR), finalized the Corsica River
       Watershed Restoration Action Strategy (WRAS). The
       plan outlined implementation strategies needed
       to protect and restore the watershed. In 2005 EPA
       accepted the Corsica River WRAS, which was high-
       lighted as one of the nation's best watershed plans
       at the CWA section 319 nonpoint source annual
       meeting. That same year, Maryland's governor
       selected the Corsica River for the state's targeted
       restoration watershed program.

       Watershed partners have worked to implement agri-
       cultural best management practices (BMPs) since
       2004. Over the last several years, farmers have annu-
       ally planted increasing acres of cover crops. Since
       2010, annual cover crop coverage has exceeded the
       WRAS goal of 3,000 acres per year. Other agricul-
       tural BMPs implemented include approximately
       5 acres of natural buffer, 30 acres of grassed buffers,
       30 acres of riparian herbaceous cover, 3 acres of
       grassed waterways and 2 miles of stream fencing.

       In 2005 the Maryland Department of Agriculture
       (MDA) received CWA section 319 funds to promote
       and partially reimburse cover crop planting on farm
       fields in the watershed. Since then,  CWA section
       319 funds have also supported  efforts by an MDA
       agricultural technician to help local farmers select
       and target agricultural BMPs.

                            In 2006 the town of
                            Centreville and Queen
                            Anne's County began a
                            series of CWA section
                            319-funded projects, includ-
                            ing urban stormwater infiltra-
                            tion projects and support
                            for education and outreach
                            efforts. Local partners
                            installed stormwater wet-
                            land ponds and bio-retention
                            practices, which capture
                            and  hold excess stormwater
                            runoff during heavy pre-
                            cipitation events. The town
                            installed stormwater retrofits
                            on 112 acres (Figure 2).
                            Local residents volunteering
       through the Corsica River Conservancy have installed
       more than 300 rain gardens.

       Maryland legislation established the Bay Restoration
       Fund in 2004. It supports upgrading WWTPs with
       enhanced nutrient removal technology, improving
       on-site septic systems and implementing cover
       crops to reduce nutrient loading to the Chesapeake
Figure 2. From 2009-2010 the
town of Centerville and MDNR
converted an existing stormwater
management pond into a multi-cell
pond-wetland complex to more
effectively capture and treat runoff.
                                                                 Bay. As of May 2012, 13 on-site septic systems in
                                                                 the Corsica River watershed were enhanced with
                                                                 nitrogen-reducing treatment capability. In 2010
                                                                 the town of Centerville completed upgrades of
                                                                 its WWTP to include biological nutrient reduction
                                                                 technology. In addition, Centerville now applies its
                                                                 WWTP discharge to farmland through spray irriga-
                                                                 tion for nine months each year, which has greatly
                                                                 reduced the amount of discharge directly entering
                                                                 the upper tidal reaches of the Corsica River.
                                                                 Results
                                                                 Monitoring data from 2005-2011 show decreasing
                                                                 trends of instream nitrogen and phosphorus con-
                                                                 centrations in the nontidal tributaries of the Three
                                                                 Bridges Branch and Gravel Run subwatershed.
                                                                 Groundwater monitoring conducted on crop fields
                                                                 in the watershed during 2005-2007 spring sampling
                                                                 periods indicates that cover crop planting may be
                                                                 reducing nutrient loadings.

                                                                 The upgrades to Centerville's WWTP have also
                                                                 reduced nutrient loading. Comparing discharge
                                                                 monitoring records from 1997 (before upgrades) to
                                                                 the period 2007-2012 (after upgrades) shows that
                                                                 total nitrogen loads from the plant have declined
                                                                 by 87 percent (from 11,175 pounds per year to
                                                                 1,424 Ib/yr) and that total phosphorus loads have
                                                                 declined by 96 percent (from 2,395 Ib/yr to 92 Ib/yr).
                                                                 Partners and Funding
Key partners have included local government enti-
ties (the town of Centreville, Queen Anne's County
and the Queen Anne's Soil Conservation District),
local watershed groups (Corsica Conservancy and
the Chester River Association), state agencies (MDE,
MDA and MDNR), and federal agencies (EPA and the
U.S. Department of Agriculture's Natural Resources
Conservation Service [NRCS]). To date, partners
have invested almost $3.5 million in nonpoint source
implementation projects. Maryland's agricultural
cost-share program and NRCS have provided fund-
ing to implement BMPs in the watershed.  From
2004 through 2012, $450,000 in federal CWA
section 319 funds supported agricultural technical
assistance to local farmers for selecting and target-
ing BMPs. Another $920,000 funded urban BMP
implementation and provided local nonpoint source
program support. As of May 2012, Maryland's Bay
Restoration Fund had provided more than  $150,000
for 13 septic system upgrades in the Corsica River
watershed. The WWTP upgrade and capital cost
of seasonal land treatment (farmland application of
discharge) totaled about $4.5 million.
PRO^
            U.S. Environmental Protection Agency
            Office of Water
            Washington, DC


            EPA841-F-13-001P
            April 2013
                                                                 For additional information contact:
                                                                 Eva Kerchner, Watershed Manager/Zoning Officer
                                                                 Town of Centreville
                                                                 410-758-1180 • ekerchner@TownofCentreville.org
                                                                 Ken Shanks, TMDL Implementation Division Chief
                                                                 Maryland Department of the Environment
                                                                 410-537-4216  • kshanks@mde.state.md.us

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