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Pacific Southwest, Region 9

Serving: Arizona, California, Hawaii, Nevada, Pacific Islands, Tribal Nations

Low Impact Development

Graphic link to the National Low Impact Development Atlas website
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EPA Pacific Southwest’s Support for Low Impact Development

EPA Pacific Southwest is a strong supporter of the use of Low Impact Development (LID) to protect water quality by managing stormwater as close to its source as possible via infiltration into soils, evapotranspiration via plants, and/or harvesting for use. LID (also known as Green Infrastructure) techniques reduce the opportunity for stormwater to run off, entrain pollutants, and discharge pollutants to waters. LID tools mimic pre-development hydrology to reduce the impact of built areas and promote the natural movement of water within a watershed, thus reducing hydromodification. Stormwater is treated as a resource, rather than a waste, conserving scarce water supplies by replenishing groundwater and capturing stormwater for beneficial use. Ancillary benefits of LID include energy conservation, ecosystem restoration, and flood control.

EPA’s Policies and Tools for the Use of Low Impact Development

Nationally, EPA has developed policies and guidance encouraging the use of LID. EPA’s Headquarters office has also compiled technical information such as research papers, models and calculations. All of these materials, and more, including links to external resources, may be found at the two EPA-HQ websites for Low Impact Development and Green Infrastructure.

Promoting the Use of Low Impact Development in the Pacific Southwest

Financial Support

Clean Water Act State Revolving Fund: The Clean Water Act State Revolving Fund (CWSRF) Program provides financing, typically via below-market rate loans, to eligible entities within state and tribal lands for water quality projects including: nonpoint source control, watershed protection or restoration, estuary management, and municipal wastewater treatment. Our Pacific Southwest Office provides grants to the states of Arizona, California, Hawaii and Nevada to capitalize individual state CWSRFs. The programs are managed by the states. Loans or other types of assistance for projects are distributed according to each state’s program and priorities.

Some examples of completed LID projects funded by the CWSRF include:

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Nonpoint Source Projects

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Nonpoint source (NPS) pollution comes from many diffuse sources when rain, snowmelt, irrigation water, and other water sources move across and through land, picking up pollutants and carrying them into lakes, rivers, wetlands, coastal waters and underground sources of drinking water. Since 1990, Congress has provided over $1.5 billion dollars nationally to address NPS pollution under the Clean Water Act, Section 319. These funds are provided to state water quality agencies and tribes to implement their NPS Management Plan. All of the states and tribes in the Pacific Southwest provide funding to local NPS implementation projects through a competitive process (and base allocation process for tribes).

The Los Angeles River Street Biofiltration Project, a Green Streets Pilot Project, is one example of LID work funded with NPS funds.

The Popoia Street Stormwater Retrofit and Rain Garden Co-op are two examples of LID efforts supported with NPS funds in Hawaii. The Rain Garden Co-op project also developed a statewide rain garden manual (PDF) (36 pp, 6.0M).

National Estuary Program

The National Estuary Program (NEP) was established in 1987 by amendments to the Clean Water Act to identify, restore and protect estuaries along the coasts of the United States. Currently, there are 28 national estuaries, including three in the Pacific Southwest, that annually receive EPA funding. The NEP focuses not just on improving water quality in an estuary, but on maintaining the integrity of the whole system-- its chemical, physical, and biological properties, as well as its economic, recreational, and aesthetic values. The following are NEP-sponsored LID programs and projects:

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LID provisions in Municipal Separate Storm Sewer System (MS4) Permits

Storm water runoff in urbanized areas is often conveyed through a municipal separate storm sewer system (MS4) before discharging into downstream water bodies. MS4s are used in modern developments to convey storm water separately from sanitary sewage, in contrast with the combined sewer systems which convey both storm water and sewage in some older cities.

The public entities that own and operate MS4s are required to develop storm water management programs and obtain MS4 permits under the National Pollutant Discharge Elimination System (NPDES) of the Clean Water Act (CWA). For more information on NPDES MS4 permits, see the national storm water website. MS4 permittees are increasingly using LID to control storm water discharges to meet CWA requirements.

Many recently renewed MS4 permits contain provisions requiring the use of LID, most commonly for new and redevelopment projects. EPA’s Pacific Southwest Office endorses the following permits containing measurable LID provisions to protect water quality:

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East Contra Costa County (PDF) (245 pp, 1.4MB)– (see page 21) – Central Valley Regional Water Quality Control Board

Orange County (PDF) (96 pp, 333K)– (see page 28 of 91, also see page 67 of 97 regarding retrofitting existing development) – San Diego Regional Water Quality Control Board

Orange County (PDF) (93 pp, 905K)– (see page 47 of 93) – Santa Ana Regional Water Quality Control Board

Riverside County (PDF) (234 pp, 2.7MB)– (see page 84 of 117) – Santa Ana Regional Water Quality Control Board

Riverside County (PDF) (93 pp, 501K) – (see page 34 of 88, also see page 66 of 88 on retrofitting existing development) - San Diego Regional Water Quality Control Board

San Bernardino County (PDF) (199 pp, 13.1MB)– (see page 72/125) – Santa Ana Regional Water Quality Control Board

San Francisco Bay Region– (see page 16) - San Francisco Bay Regional Water Quality Control Board

City of Santa Rosa & Sonoma County (PDF) (68 pp, 431K)– (see page 35 of 68) – North Coast Regional Water Quality Control Board

Ventura County (PDF) (133 pp, 8.3MB)– (see page 53) – Los Angeles Regional Water Quality Control Board

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State and Local Initiatives

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  • City of San Francisco – The San Francisco Stormwater Design Guidelines require new development and redevelopment disturbing 5,000 square feet or more of the ground surface to manage stormwater on-site. The Guidelines show project applicants how to achieve on-site stormwater management using LID strategies, also known as green infrastructure.
  • City of Santa Monica - On July 27, 2010, the City of Santa Monica’s City Council approved an updated Urban Runoff Pollution Ordinance (PDF) (34 pp, 1.8MB) requiring the use of LID for new development/redevelopment projects.

Other Recommended Resources

This section includes material on aspects of LID in the Pacific Southwest that may be valuable for those implementing LID:

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