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National Pollutant Discharge Elimination System (NPDES)
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Permit Limits-Watershed-Based Permitting

NPDES Permit Limits Topics
  • Overview
  • TBELs and WQBELs
  • Nutrient Permitting
  • Recreational Water Quality Criteria Limits
  • TMDL Permitting
  • Watershed-based Permitting
  • Whole Effluent Toxicity (WET)
  • Additional Resources
On this page:
  • Watershed-Based Permitting Basics
  • Policy and Guidance
  • Case Studies
  • Additional Resources

Watershed-Based Permitting Basics

Watershed-based permitting may include a variety of activities, ranging from synchronizing permits within a basin to developing water quality-based effluent limits using a multiple discharger modeling analysis. Implementation of watershed-based permitting can lead to a variety of outcomes including, improved environmental results; more effective implementation of total maximum daily loads (TMDLs) and watershed management plans; facilitation of water quality trading and other market-based strategies; and improved opportunities for stakeholder involvement.

There are a variety of permitting approaches that EPA considers to be watershed-based. Selecting the appropriate approach will depend on the unique characteristics of the watershed and the sources of pollution affecting it. The three main types of watershed-based permits include:

  • Integrated municipal permits. Integrated municipal permits bundle permit requirements for a number of point sources (e.g., publicly owned treatment works [POTWs], combined sewer overflows, municipal separate storm sewer systems [MS4s], and stormwater from municipally owned industrial activities, such as public works and utility yards) for a municipality or multiple municipalities within a watershed or covering multiple watersheds into a single permit.
  • Multisource watershed-based permits. A multisource watershed-based permit uses a single permit for multiple sources in the same watershed.
  • Coordinated individual permits. Coordinated individual permits include water quality-based effluent limitations and other conditions developed using a holistic analysis of the watershed conditions. Coordinated individual permits sometimes include synchronized expiration and reissuance or effective dates.

Policy and Guidance

EPA has long encouraged watershed approaches to addressing water quality problems. Since 2003, EPA has developed a variety of policy and guidance documents to support the implementation of watershed-permitting approaches.

  • Watershed-Based NPDES Permitting Policy Statement Memorandum (pdf) (154.07 KB) (2003) - Describes the benefits of watershed-based permitting and the implementing mechanisms for this component of the watershed approach.
  • Watershed-Based NPDES Permitting Implementation Guidance (pdf) (1.65 MB) (2003) - Describes EPA's recommended process for developing and implementing watershed-based permits, identifies benefits and potential challenges of this approach, and provides resources and references for stakeholders.
  • Watershed-Based NPDES Permitting Technical Guidance (pdf) (2.03 MB) (2007) - A follow-up to the 2003 Watershed-based NPDES Permitting Implementation Guidance; provides detailed guidance to help permitting authorities develop and issue watershed-based permits that fit into an overall watershed planning and management approach with input from stakeholders.

Case Studies

To promote the innovative watershed-based permitting approach, EPA has generated a case study series highlighting EPA and state watershed-based permitting activities.

Click on the map and see the list below to learn how states are implementing watershed-based permitting approaches to achieve their water quality protection goals.

Integrated Municipal Permits

  • Tualatin River Watershed, Oregon: Clean Water Services Integrated Municipal Permit (Revised July 2007) (pdf) (1.2 MB) - Summarizes Oregon’s integrated municipal permit for Clean Water Services, which incorporates requirements for its four municipal wastewater treatment facilities, MS4 and industrial stormwater. The permit allows water quality trading for temperature, biochemical oxygen demand and ammonia as a compliance option for meeting TMDL wasteload allocations.
  • Northern Kentucky Sanitation District No. 1: Permitting Approach (pdf) (37.31 KB) - Describes a pilot project to evaluate the feasibility of implementing a watershed-based permitting approach for municipal wastewater and stormwater discharges in three counties in northern Kentucky.

Multisource Watershed-Based Permits

  • General Permit for Nitrogen Dischargers in Long Island Sound: Final Permit (Revised March 2008) (pdf) (1.14 MB) - Provides an overview of Connecticut’s Nitrogen General Permit, which covers 79 POTWs in Long Island Sound. The general permit allows permittees to achieve compliance with TMDL wasteload allocations for total nitrogen through participation in the Nitrogen Credit Exchange Program. 
  • Chesapeake Bay Watershed, Virginia: Watershed-based General Permit for Nutrient Discharges and Nutrient Trading (July 2007) (pdf) (1.22 MB) - Provides an overview of Virginia’s general permit for nutrient discharges in the Chesapeake Bay. The general permit implements TMDL wasteload allocations for total nitrogen and total phosphorus and allows facilities to exchange credits, either individually or through the Nutrient Credit Exchange Association, to comply with their effluent limitations.
  • Neuse River Watershed, North Carolina: Neuse River Compliance Association Watershed-Based Permit (Revised July 2007) (pdf) (1.19 MB) - Highlights North Carolina’s watershed-based permit for 21 co-permittees that make up the Neuse River Compliance Association to address discharges of total nitrogen to the Neuse River. The permit allows for compliance with TMDL wasteload allocations through a group limit for members of the association and water quality trading.
  • Michigan Statewide Stormwater Permitting: Statewide Watershed-Based MS4 Stormwater General Permit (Revised July 2007) (pdf) (1.24 MB) - Highlights the development of the Rouge River watershed-based MS4 permit and its adaptation for use as a statewide general permit called the “Watershed-Based Permit.” The Watershed-Based Permit provides a watershed approach for implementing and coordinating compliance efforts for municipal stormwater as an alternative to the state’s Jurisdictional Permit, a more traditional MS4 general permit.
  • Cherry Creek Reservoir Drainage Basin, Colorado: Municipal Separate Sewer Systems, Phase II Stormwater Permit (pdf) (1.27 MB) - Describes Colorado’s watershed-based general permit for municipal stormwater in the Cherry Creek Reservoir watershed. The permit requirements implement regulations designed to meet total phosphorus and chlorophyll-a criteria and protect the reservoir’s beneficial uses of warm-water aquatic life habitat, contact recreation, drinking water supply and agricultural supply.
  • Waste Discharge Requirements for South Lake Tahoe, El Dorado County and Placer County (pdf) (1001.83 KB) - Summarizes the State of California, Lahontan Regional Water Quality Control Water Board’s general permit for municipal stormwater for three MS4s in the Lake Tahoe watershed. The general permit eliminated the need for coverage under multiple permits and includes requirements for discharges of sediment and nutrients to restore water quality in Lake Tahoe.
  • Industrial Stormwater Discharges from Dredging at Marinas in Lake Tahoe (pdf) (1001.33 KB) - Summarizes the State of California, Lahontan Regional Water Quality Control Board’s general permit for industrial stormwater and maintenance dredging for 12 marinas in the Lake Tahoe watershed. The general permit combines two separate—but similar—permits and their monitoring and reporting requirements, providing a more streamlined permitting process.
  • Construction Stormwater Discharges from Land Disturbance in Lake Tahoe (pdf) (1004.29 KB) - Provides an overview of the State of California, Lahontan Regional Water Quality Control Board’s general permit for construction stormwater in the Lake Tahoe watershed. The general permit includes stormwater limitations developed for the Lake Tahoe watershed and additional monitoring requirements for restoration and habitat improvement projects to measure their success.
  • Big Darby Creek Watershed, Ohio: Construction Watershed-Based General Permit (pdf) (1.15 MB) - Describes Ohio’s general permit for construction stormwater in the Big Darby Creek watershed, a state and national scenic river. The multisource watershed-based permit includes requirements necessary to achieve TMDL and water quality management plan goals for the watershed, including riparian setback, groundwater recharge and mitigation requirements.
  • Lake Lewisville Watershed, Texas: City of Denton Watershed Protection Program (July 2007) (pdf) (1.17 MB) - Summarizes the City of Denton’s proactive watershed approach to protect the Lake Lewisville watershed, an important source of drinking water, and comply with their municipal stormwater permit requirements. The city’s Watershed Protection Program consists of extensive watershed-based monitoring, land use management and public education.

Coordinated Individual Permits

  • Case studies coming soon.

Coordinated Watershed Monitoring

  • Cache la Poudre River, Colorado (December 2009) (pdf) (1.32 MB) - Highlights a coordinated watershed monitoring effort in the Cache la Poudre River watershed that provided efficiencies and cost savings and helped shape Colorado’s monitoring policy. The Kodak Colorado Division led the effort, working with local facilities, the Colorado Department of Public Health and the Environment and U.S. EPA Region 8.

Statewide Approaches

  • North Carolina Statewide Approach: Basinwide Planning and Permitting (Revised December 2009) (pdf) (963.96 KB) - Covers North Carolina’s watershed approach for protecting the state’s water resources, which includes planning, monitoring, modeling, permitting and compliance assessment at the basin scale. North Carolina implement this approach to achieve improved efficiency, increased effectiveness, and consistency and equitability.
  • Tennessee Statewide Approach: Watershed Management Approach (December 2009) (pdf) (1.19 MB) - Describes Tennessee’s watershed approach for meeting the state’s clean water goals, which includes planning, monitoring, assessment, TMDL development and permitting activities on a rotating 5-year schedule. Tennessee designed their programmatic approach to achieve efficiency, effectiveness and equitability.

Additional Resources

Watershed-based permitting approaches can be driven by a wide array of watershed management activities, such as local or state watershed management planning, TMDL implementation, and modifications to water quality standards. As state permitting authorities and other watershed stakeholders look for solutions to complex water quality challenges, watershed-based permitting has emerged as a way to implement integrated planning, adaptive management, green infrastructure for stormwater management, and market-based approaches into the NPDES program. For more information about these other management activities, see the resources below.

  • Healthy Watersheds Protection – EPA created the Healthy Watersheds Program to emphasize proactively protecting high-quality waters following the Clean Water Act's (CWA’s) objective “…to restore and maintain the chemical, physical, and biological integrity of the Nation’s waters.”
  • CWA Section 303(d): Impaired Waters and TMDLs – Section 303(d) of the CWA authorizes EPA to assist states, territories and authorized tribes in listing impaired waters and developing TMDLs for these waterbodies.
  • Nutrient Pollution – Nutrient pollution, such as excess nitrogen and phosphorus in water, is one of America’s most widespread, costly and challenging environmental problems.
  • Nutrient Permitting – Permits are required for any point source discharge of pollutants to U.S. waters. Point sources regulated by the NPDES program that discharge nutrients include municipal and industrial wastewater treatment plants, concentrated animal feeding operations, MS4s, stormwater associated with industrial activity, and various other potential sources of nutrient pollution.
  • Water Quality Trading – Water quality trading under the CWA is an option for compliance with effluent limitations in some NPDES permits.
  • Water Quality Standards – Water quality standards define the water quality goals of a waterbody by designating the uses of the water and by setting criteria to protect those uses.
  • Source Water Protection – Source water protection includes a wide variety of actions and activities aimed at safeguarding, maintaining, or improving the quality and/or quantity of sources of drinking water and their contributing areas.
  • Integrated Planning – Integrated planning offers a voluntary opportunity for municipalities to propose to meet multiple CWA requirements by identifying efficiencies from separate wastewater and stormwater programs and sequencing investments.
  • Green Infrastructure – Green infrastructure practices use vegetation, soils and natural processes to manage water and create healthier urban environments.
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Last updated on December 29, 2022
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