Water Quality Management Using the National Pollutant Discharge Elimination System (NPDES) Watershed Framework: EPA’s New Technical Guidance

For nearly a decade, EPA has supported and encouraged a watershed approach to addressing water quality problems. In December 2002, the EPA Office of Water Assistant Administrator issued a policy memo titled, “Committing EPA’s Water Program to Advancing the Watershed Approach.” Through this memo, EPA reaffirmed its commitment to the watershed approach and reenergized efforts to ensure that EPA fully integrates the approach into program implementation. After the policy memo, EPA released the “Watershed-Based NPDES Permitting Policy Statement,” which committed EPA to the development of resources to facilitate implementation of watershed-based permitting (EPA 2003a). In December 2003, EPA released the Watershed-Based National Pollutant Discharge Elimination System Permitting Implementation Guidance [EPA 833-B-03-004] to fulfill part of the commitment made in the policy statement (EPA 2003b).

The NPDES program is just one of a multitude of environmental programs that may come into play within a watershed; however, EPA has long recognized that the NPDES program has a significant role in structuring a watershed approach to environmental management. The 1994 “NPDES Watershed Strategy” reflects EPA’s earliest support for applying a watershed approach to NPDES permitting. In this Strategy, EPA states, “The NPDES program occupies a unique position within the overall water program, since it is both a key customer and an essential partner in supporting other  office of Water program activities and achieving many of our broader water quality goals.” The following list illustrates the linkages between the NPDES program and the other Office of Water programs:

  • NPDES permits implement portions of Total Maximum Daily Loads (TMDLs) and other watershed plans.
  • Water quality standards decisions affect the content of NPDES permits as well as potential treatment or process changes that point sources consider.
  • Point source discharges may impact the hydrology of a stream and the structure of an aquatic community.
  • Sources of runoff are either subject to NPDES program requirements (e.g., municipal and industrial stormwater) or representative of potential nonpoint source trading partners for point sources in a water quality trading program.
  • NPDES permit conditions may be written specifically to protect sources of
    drinking water.

Because of the critical role that point sources and NPDES permits play in many water quality management decisions and the connections between NPDES permits and other aspects of water quality management, establishing an NPDES watershed framework will be a key to the success of an integrated water quality management approach in many watersheds.

The watershed approach is characterized by the use of a dynamic process to identify and assess problems holistically and implement site-specific solutions to achieve watershed goals. Therefore, the process for integrating the NPDES permitting program into a larger watershed management system means developing and utilizing a watershed-based analytical approach to coordinate NPDES activities with other water quality activities. A watershed-based analytical approach is the groundwork data collection and analysis conducted to support the development and issuance of NPDES permits that consider the diverse pollutant sources and stressors located within a defined geographic area (i.e.,
watershed boundaries). The primary difference between a watershed permitting analytical approach and the more common historical approach to permitting is that the watershed permitting analytical approach considers the impact of multiple pollutant sources and stressors, including nonpoint source contributions. In contrast, the historical approach simply uses an aggregate background load. A watershed permitting analytical approach also considers watershed goals throughout the permitting process.

The conclusions reached through the watershed-based analytical approach are then implemented through a broad range of possible NPDES implementation options to achieve watershed goals. These options extend beyond the traditional approach of developing and issuing a single NPDES permit to an individual point source discharger. This broader view of NPDES implementation options is referred to as the NPDES watershed framework, and the NPDES watershed framework serves as a structure to manage implementation of the NPDES program on a watershed basis. The framework provides a variety of permitting options and tools that can be used to implement a watershed approach. The specific permitting options and tools used in the framework will depend on the characteristics of the watershed and the permitting context.

This paper and presentation will further discuss the concepts of a watershed permitting analytical approach and an NPDES watershed framework, including several permitting tools and options that a framework may include. The paper and presentation will also highlight EPA’s current activities in developing guidance to assist NPDES permit writers and permittees throughout implementation of a watershed approach. This guidance will build on the existing Policy and Implementation Guidance that are already available to the public.

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