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Water: Green Infrastructure

Federal Regulatory Programs

Regulatory drivers can provide an effective foundation for the consistent implementation of green infrastructure across a community, state, or region. This section discusses 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). For guidance on integrating green infrastructure into local codes and ordinances see Policy Guides.

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EPA Policy Memo
Policy Memos
EPA strongly encourages the use of green infrastructure approaches to manage wet weather. Since 2007, EPA’s Office of Water has released four policy memos supporting the integration of green infrastructure into NPDES permits and CSO remedies.

Memorandum, Achieving Water Quality Through Integrated Municipal Stormwater and Wastewater Plans (PDF) (3 pp, 1.1MB) – In October 2011, EPA’s Office of Water (OW) and Office of Enforcement and Compliance Assurance (OECA) issued a joint memo encouraging EPA Regions to assist their state and local partners in pursuing an integrated planning approach to Clean Water Act waste and stormwater obligations.  The memo identifies green infrastructure as one example of a comprehensive solution that can improve water quality while supporting other quality of life attributes that enhance the vitality of communities.

Memorandum, Protecting Water Quality with Green Infrastructure in Water Permitting and Enforcement Programs (PDF) (5 pp, 343K) – In April 2011, EPA OW and OECA jointly issued a memo supporting the use of green infrastructure. The memo reaffirms the commitment of both offices to work with interested communities on incorporating green infrastructure into stormwater permits and into remedies for non-compliance with the Clean Water Act.

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, 215K) - In June 2008, EPA issued a memo reaffirming its support of the use of infiltration practices for managing stormwater, and providing an overview of UIC program requirements for stormwater infiltration practices that are classified as Class V wells. The memo is supported by a guide describing the major types of stormwater infiltration practices and explaining which practices are generally considered class V wells.

Memorandum, Use of Green Infrastructure in NPDES Permits and Enforcement (PDF) (2 pp, 924K) - In August, 2007, EPA issued a memo encouraging the incorporation of green infrastructure into National Pollutant Discharge Elimination System (NPDES) stormwater permits and CSO long-term control plans. Additionally, the memo states that green infrastructure can and will be used in future EPA enforcement activities.

Memorandum, Using Green Infrastructure to Protect Water Quality in Stormwater, CSO, Nonpoint Source and other Water Programs (PDF) (2 pp, 156K) - In March, 2007 Benjamin Grumbles, EPA's Assistant Administrator for Water, issued this memo to promote green infrastructure as a viable stormwater management solution.

Green Infrastructure Permitting and Enforcement Series
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 six factsheets and four supplements addressing general accountability considerations; CSOs; SSOs; stormwater; TMDLs; and water quality standards. The series includes sample language and case studies to illustrate the concepts discussed.
Factsheet 1: General Accountability Considerations for Green Infrastructure (PDF) (8 pp, 1.8MB) - Accountability considerations are important in all actions involving permits or enforcement orders, regardless of the approaches used to achieve compliance with established standards. This factsheet discusses six accountability mechanisms that may be applied to permits or enforcement actions that include green infrastructure.

Factsheet 2: Combined Sewer Overflows (PDF) (8 pp, 2.8MB) - Green infrastructure can reduce the volume of stormwater entering combined sewer systems during precipitation events, which may reduce numbers and volumes of overflows. This factsheet addresses the evaluation of green infrastructure approaches for CSO control, the identification of quantitative implementation targets, and the incorporation of green infrastructure approaches into Long Term Control Plans.

Factsheet 3: Sanitary Sewer Overflows (PDF) (6 pp, 1.2MB) - Depending on the causes of SSOs for a particular system, green infrastructure approaches may be used in conjunction with gray infrastructure improvements and capacity, management, operations and maintenance (CMOM) to help eliminate SSOs. This factsheet discusses how green infrastructure approaches may be integrated into CMOM plans and CSO consent decrees.

Factsheet 4: Stormwater (PDF) (8 pp, 1.1MB) - Much of the aquatic ecosystem degradation associated with stormwater is caused by changes in discharge volumes, rates, and durations. This factsheet discusses how green infrastructure can be integrated into stormwater permits to maintain more natural flow regimes.

Factsheet 5: Total Maximum Daily Loads (PDF) (6 pp, 1.7MB) - Many 303(d)-listed waters are impacted by changes in natural hydrology associated with urbanization. This factsheet describes how Total Maximum Daily Loads (TMDLs) and TMDL implementation plans (IPs) can address the hydrological factors that contribute to impairments by including green infrastructure.

Factsheet 6: Water Quality Standards (PDF) (4 pp, 1.3MB) - Water quality standards include designated uses, water quality criteria, and an antidegradation policy and implementation procedures. This factsheet 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 (PDF) (8 pp, 2MB) - This supplement to Factsheet 2 summarizes the green infrastructure provisions in seven CSO consent decrees entered since 2003.

Supplement 2: Consent Decree Language Addressing Green for Gray Substitution (PDF) (8 pp, 4MB) - This supplement to Factsheet 2 provides an excerpt from the 2010 settlement with the Northeast Ohio Regional Sewer District (NEORSD) to address the flow of untreated sewage into Cleveland waterways and Lake Erie.

Supplement 3: Green Infrastructure Models and Calculators (PDF) (4 pp, 1MB) - This supplement to Factsheet 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 (PDF) (8 pp, 1.6MB) - This supplement to Factsheet 5 summarizes two recent TMDLS that address flow, hydrology, and green infrastructure.

Discharge Pipe
MS4 Permits
EPA requires operators of municipal separate storm sewer systems (MS4s) to obtain an NPDES permit and develop a stormwater management program.   In recent years, more and more cities and states are integrating provisions promoting or requiring green infrastructure into their MS4 permits. Here we highlight a few recent examples.  Many more examples can be identified by contacting your state or Regional NPDES permitting authority.

California Exit EPA Disclaimer - Since May 2009, the California Regional Water Quality Control Boards have adopted nine Phase I MS4 permits requiring that new development and redevelopment projects retain the 85th percentile storm event via infiltration, evapotranspiration, and rainwater harvest and reuse by utilizing green infrastructure practices. Within the individual permits, there are provisions that allow for off-site mitigation or payment of fees if retention and biofiltration are not technically feasible on site.
Massachusetts (PDF) (58 pp, 276K)- EPA's draft MS4 General Permit for North Coastal Massachusetts encourages the use of practices which 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 for their ability to support green infrastructure options in new development and redevelopment, identify impediments, and determine what changes need to be made.
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, along with 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). 
Greening CSO Plans
CSO Control Plans and Remedies
Green infrastructure can reduce the volume and occurrence of combined sewer overflows, 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 non-compliance with the CSO Control Policy.  Here we highlight a recent EPA tool and a few examples of cities that have integrated green infrastructure into their CSO control plans.  Many more examples can be identified by contacting your state or Regional NPDES permitting authority.

Greening CSO Plans: Planning and Modeling Green Infrastructure for Combined Sewer Overflow (CSO) Control (PDF) (38 pp, 2MB) – 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.

Review of Green Infrastructure (GI) in CSO Long Term Control Plans: A Training Tool – Produced by EPA Region 5 and EPA's Office of Enforcement and Compliance Assurance (OECA), this resource provides additional insight into how to assess the practicality and likely performance of green infrastructure measures within CSO Long Term Control Plans.

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 Clean Water Act (CWA) settlements. This link contains an index of recent U.S. 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.  

Storm Drain Inlet
Urban stormwater is a primary cause of water quality impairment for thousands of water bodies across the United States. Under Section 303(d) of the Clean Water Act, states, territories, and authorized tribes are required to establish priority rankings for impaired waters and develop TMDLs for these waters. Green infrastructure practices that infiltrate, evapotranspire, and capture and use rainwater represent one approach that these jurisdictions can take to meet waste load allocations for urban stormwater. 

Incorporating Green Infrastructure Concepts into Total Maximum Daily Loads (TMDLs) (PDF) (11 pp, 253K) – This EPA fact sheet summarizes how green infrastructure/low impact development practices can be incorporated into TMDLs, and examines how these concepts have been applied in two recent TMDLs.
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 first designated all stormwater discharges from contiguous impervious areas greater than two acres in three target municipalities as discharges requiring NPDES permits, then developed a draft general permit.  

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