v>EPA

Nutrient Reduction Case Study
Storm water Retention Credit (SRC) Program
Washington, D.C.

Stormwater runoff, polluted by contact with impervious surfaces, is commonly transported
through municipal separate storm sewer systems (MS4), which discharge to local waterbodies.
Green infrastructure, such as rain gardens and green roofs, can reduce stormwater pollution by
capturing and filtering runoff, recharging groundwater, and reusing water for irrigation or other
non-potable uses.

Washington, D.C.'s National Pollutant Discharge Elimination System (NPDES) permit for MS4s
addressed this pollution through innovative stormwater management techniques focusing on
reducing runoff and improving water quality. The permit includes an option for the D.C.
Department of Energy and the Environment (DOEE) to develop an offsite mitigation program,
called the Stormwater Retention Credit (SRC) program. The SRC program allows stormwater
projects to be implemented offsite rather than onsite and promotes effective stormwater
management at a lower cost than traditional program requirements.

Under the MS4 permit's SRC program, voluntary
green infrastructure stormwater retention
credits can be generated by large construction
projects; one credit equals one gallon of runoff
retention for one year. These green
infrastructure investments generally cost less
than if the city did the work itself. This unique
program focuses on creating green infrastructure
in areas that drain to small tributaries in the MS4,
and includes additional support to accelerate the
credit trading market:

•	SRC Price Lock Program: Launched in 2017 with an $11.5 million commitment, eligible
SRC generators may sell credits to DOEE at fixed prices for projects where untreated
runoff drains to the MS4. This effectively creates a price floor for D.C.'s SRC market and
offers revenue certainty for projects.

•	SRC Aggregator Startup Grant: Provides up to $75,000 in grants to SRC generators for
site evaluation for green infrastructure feasibility, including technical support and
outreach to identify projects in the MS4. This helps SRC generators develop projects for
enrollment in the SRC Price Lock Program described above.

•	SRC Site Evaluation Program. Free technical assistance to assess opportunities for SRC
generation to land owners with at least a half-acre of land in the MS4 area, with a
preference for properties owned by non-profits. Financial assistance not provided.

Additional Information

SRC Program: https://doee.dc.gov/src

Stormwater Credit Trading:

https://www.youtube.com/watch?v=dfFoeQ40TMw;

https://www.voutube.com/watch?v=ZSXF9TfZ4sA;

https://www.voutube.com/watch?v=Sat4-EvGSA4

Learn more at: https://www.epa.gov/nutrient-policy-data

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In addition to the SRC Price Lock Program, credit generators may also sell SRCs in an open
market to properties managing stormwater runoff through a public SRC Registry where buyers
and sellers independently negotiate a final purchase price. A site may opt to pay an in-lieu fee
to achieve offsite retention obligations instead of buying and using SRCs.

The program has grown exponentially since the first SRCs were certified. The first SRCs were
certified in April 2014 and the first trade was approved in September 2014, for 11,013 credits
valued at $25,000. In FY 2019, the SRC market experienced 27 trades for a total of 193,158
credits valued at nearly $350,000. As a direct result of the SRC Trading Program, 15.4 acres
have been retrofitted with green infrastructure, with another 9.6 acres in
design/permitting/construction. In total, that green infrastructure results in a new retention
capacity of 466,000 gallons.

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