Green Infrastructure

Integrating Green Infrastructure into Federal Regulatory Programs

Regulatory drivers can provide an effective foundation for consistent implementation of green infrastructure across a community, state, or region. Learn how green infrastructure can be integrated into federal regulatory programs for municipal separate storm sewer systems (MS4s), combined sewer overflows (CSOs), and Total Maximum Daily Loads (TMDLs).

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Policy Memos

EPA strongly encourages the use of green infrastructure approaches to manage wet weather. Since 2007, EPA’s Office of Water has released these policy memos that support integrating green infrastructure into National Pollutant Discharge Elimination System (NPDES) permits and CSO remedies.

Memorandum, Achieving Water Quality through Integrated Municipal Stormwater and Wastewater Plans—In October 2011, EPA’s Office of Water (OW) and Office of Enforcement and Compliance Assurance (OECA) issued this joint memo encouraging EPA Regions to assist their state and local partners in pursuing an integrated planning approach to Clean Water Act (CWA) waste and stormwater obligations. The memo identifies green infrastructure as one comprehensive solution that can improve water quality and provide other benefits that enhance the vitality of communities.

Memorandum, Protecting Water Quality with Green Infrastructure in Water EPA Permitting and Enforcement Programs—In April 2011, EPA OW and OECA jointly issued this memo supporting the use of green infrastructure. The offices reaffirm their commitment to working with interested communities to incorporate green infrastructure into stormwater permits and remedies for noncompliance with the CWA.

Memorandum, Clarification on which Stormwater Infiltration Practices/Technologies Have the Potential To Be Regulated as "Class V" Wells by the Underground Injection Control (UIC) Program(PDF)(6 pp, 215 KB, About PDF)—In June 2008, EPA issued this memo reaffirming its support of using infiltration practices to manage stormwater and clarifying UIC program requirements for stormwater infiltration practices that can be classified as Class V wells.

Memorandum, Use of Green Infrastructure in NPDES Permits and Enforcement—In August 2007, EPA issued this memo encouraging the incorporation of green infrastructure into NPDES stormwaterpermits and CSO long-term control plans. The memo also pledged that EPA could and would use green infrastructure in its future enforcement activities.

Memorandum, Using Green Infrastructure To Protect Water Quality in Stormwater, CSO, Nonpoint Source and other Water Programs—In March 2007, Benjamin Grumbles, EPA's Assistant Administrator for Water, issued this memo to promote green infrastructure as a viable stormwater management solution.

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Permitting and Enforcement Series

The Green Infrastructure Permitting and Enforcement Series provides EPA and state permitting and enforcement professionals with a guide to integrating green infrastructure approaches into NPDES wet weather programs. The series consists of fact sheets and supplements on integrating green infrastructure concepts into permitting, enforcement, and water quality standards actions. The series includes sample language and case studies to illustrate the concepts presented.

Fact Sheet 1: General Accountability Considerations for Green Infrastructure—Accountability considerations are important in all actions involving permits or enforcement orders, regardless of the approaches used to achieve compliance with established standards. This fact sheet discusses six accountability mechanisms that can be applied to permits or enforcement actions that include green infrastructure.

Fact Sheet 2: Combined Sewer Overflows—Green infrastructure can reduce the volume of stormwater entering combined sewer systems during precipitation events, possibly reducing the numbers and volume of overflows. This fact sheet addresses evaluating green infrastructure approaches for CSO control, identifying quantitative implementation targets, and incorporating of green infrastructure approaches into long-term control plans.

Fact Sheet 3: Sanitary Sewer Overflows—Depending on the causes of SSOs for a particular system, green infrastructure approaches can be used in conjunction with gray infrastructure improvements and capacity, management, operations, and maintenance (CMOM) to help eliminate SSOs. This fact sheet discusses how green infrastructure approaches can be integrated into CMOM plans and CSO consent decrees.

Fact Sheet 4: Stormwater—Much of the aquatic ecosystem degradation associated with stormwater is caused by changes in discharge volumes, rates, and durations. This fact sheet discusses how green infrastructure can be integrated into stormwater permits to maintain more natural flow regimes.

Fact Sheet 5: Total Maximum Daily Loads—Many 303(d)-listed waters are impacted by changes in natural hydrology associated with urbanization. This fact sheet describes how TMDLs and TMDL implementation plans (IPs) can address the hydrological factors that contribute to impairments by including green infrastructure.

Fact Sheet 6: Water Quality Standards—Water quality standards include designated uses, water quality criteria, and an antidegradation policy and implementation procedures. This fact sheet describes how green infrastructure approaches can be considered as part of an antidegradation review or use attainability analysis.

Supplement 1: Consent Decrees that Include Green Infrastructure Provisions—This supplement to Fact Sheet 2 summarizes the green infrastructure provisions in seven CSO consent decrees entered since 2003.

Supplement 2: Consent Decree Language Addressing Green for Gray Substitutions—This supplement to Fact Sheet 2 provides an excerpt from the 2010 settlement with the Northeast Ohio Regional Sewer District to address the flow of untreated sewage into Cleveland waterways and Lake Erie.

Supplement 3: Green Infrastructure Models and Calculators—This supplement to Fact Sheet 2 summarizes the features of 19 models that can be used to predict the performance and/or cost of green infrastructure approaches.

Supplement 4: Green Infrastructure in Total Maximum Daily Loads—This supplement to Fact Sheet 5 summarizes two recent TMDLs that address flow, hydrology, and green infrastructure.

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MS4 Permits

Each operator of an MS4 is required to obtain an NPDES permit and develop a stormwater management program. An increasing number of cities and states are integrating green infrastructure provisions into their MS4 permits. Here are some examples. You can contact your state or Regional NPDES permitting authority for more examples.

California —Since May 2009, the California regional water quality control boards have adopted nine Phase I MS4 permits requiring new development and redevelopment projects to use green infrastructure practices to retain the 85th percentile storm event via infiltration, evapotranspiration, and rainwater harvest and reuse. Within the individual permits, provisions allow for off-site mitigation or payment of fees if retention and biofiltration are not technically feasible on-site.

Massachusetts (PDF)(58 pp, 276 K, About PDF)—EPA's draft MS4 General Permit for North Coastal Massachusetts encourages the use of practices that capture (infiltrate, evapotranspire, and/or harvest and reuse rainwater) the 90th percentile storm event (1-inch storm). The draft permit also requires municipalities to examine existing guidelines and policies to:

  • determine their ability to support green infrastructure options in new development and redevelopment,
  • identify impediments, and
  • identify any necessary changes.

Washington, DC—The District's MS4 permit includes:

  • a development retention standard of 1.2 inches for all development projects greater than or equal to 5,000 square feet,
  • numeric targets for green roofs (350,000 square feet over the permit cycle on District properties), and
  • tree canopy (4,150 trees/yr and 13,500 by 2014).

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CSO Control Plans and Remedies

Green infrastructure can reduce the volume and occurrence of CSOs, often while providing cost savings and creating more livable communities. EPA supports the integration of green infrastructure approaches into long term control plans for small communities and into remedies for noncompliance with the CSO Control Policy. Here you can learn about EPA tools and examples of cities that have integrated green infrastructure into their CSO control plans. You can contact your state or Regional NPDES permitting authority for more examples.

Greening CSO Plans: Planning and Modeling Green Infrastructure for Combined Sewer Overflow (CSO) Control—In March 2014, EPA released a planning resource to provide municipalities and sewer authorities with tools to help quantify green infrastructure contributions to an overall CSO control plan. Communities with combined sewers often view green infrastructure as an attractive way to reduce stormwater flows going into the sewer system, thus helping to reduce capital and operational costs at publicly owned treatment works (POTWs). This resource explains how to use modeling tools such as EPA's Storm Water Management Model (SWMM) to optimize different combinations of gray and green infrastructure.

Settled EPA Clean Water Act Enforcement Matters with Green Infrastructure Components—EPA enforcement has taken a leadership role in the incorporation of green infrastructure remedies in municipal CWA settlements. This link contains an index of EPA enforcement actions incorporating green infrastructure.

EPA Green LTCP-EZ Template—In July 2011, EPA released an updated LTCP-EZ template incorporating several green infrastructure controls. Small CSO communities can use this template to assess the potential for green infrastructure controls to eliminate or reduce CSOs. Communities should consult with their permitting authorities to determine whether it is appropriate for them to use all or some portions of the Green LTCP-EZ Template.

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Urban stormwater is a primary cause of water quality impairment in thousands of water bodies across the country. States, territories, and authorized tribes are required to establish priority rankings for impaired waters and develop TMDLs for the waters under section 303(d) of the CWA. Green infrastructure practices that infiltrate, evapotranspire, and capture and use rainwater can be used to meet waste load allocations for urban stormwater.

Incorporating Green Infrastructure Concepts into Total Maximum Daily Loads (TMDLs)(PDF)(11 pp, 254 KB, About PDF)—This EPA fact sheet summarizes how green infrastructure/low impact development practices can be incorporated into TMDLs and examines two case studies.

Charles River Watershed, MA—In 2007, EPA approved a TMDL for phosphorus discharges to the lower Charles River. To achieve the required reductions in phosphorus loads, EPA Region 1 developed an approach that encourages the use of green infrastructure to retain and treat stormwater. Region 1:

  • designated all stormwater discharges from contiguous impervious areas greater than 2 acres in three target municipalities as discharges requiring NPDES permits; and
  • developed a draft general permit.

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