Watershed-scale Management Tools


The following is a collection of resources to aid in the creation, implementation, and understanding of a watershed-scale management plan. This list should not be considered a comprehensive list as there are many tools across the nation that could be adapted for watersheds in Washington State. This list will continue to change as new tools are created and the science of watershed management advances.


System for Urban Stormwater Treatment and Analysis IntegratioN (SUSTAIN)

SUSTAIN is a decision support system that assists stormwater management professionals with developing and implementing plans for flow and pollution control measures to protect source waters and meet water quality goals. SUSTAIN allows watershed and stormwater practitioners to develop, evaluate, and select optimal best management practice combinations at various watershed scales based on cost and effectiveness.

Stormwater Control Transfer Program

The Department of Ecology has also recently issued a draft document that provides guidance on a Stormwater Control Transfer Program. The draft guidance document lays out features of an alternative program (a Stormwater Control Transfer Program) that Western Washington State Municipal Stormwater Permittees can implement to satisfy permit requirements associated with flow control, runoff treatment, and/or low impact development triggered at new and redevelopment sites. For more information, see

Washington Stormwater Center

The Washington Stormwater Center has a Municipal Resource Program that provides assistance to stormwater permittees by providing a clearinghouse of resources, answering permit questions, and developing training programs. The program focuses on assisting with both Phase I and Phase II Municipal permits both in Western Washington and Eastern Washington.

Total Maximum Daily Loads (TMDLs)

TMDLs are a calculation of the maximum amount of a pollutant that a waterbody can receive from both point and nonpoint sources and still meet water quality. Point source allocations in TMDLs provide water quality targets for point sources such as wastewater treatment plans and stormwater treatment systems that go into their regulatory permits. Nonpoint source allocations are usually managed according to a TMDL implementation plan or watershed-based plan. Provides an important starting point for water quality planning. The TMDL process starts with identifying pollution sources within a watershed and helps determine what needs to change so that pollution is reduced or eliminated.

Characterization Study

A watershed characterization is a science-based examination of the features in a watershed and how those features interact to affect the watershed's natural environment. A characterization study provides baseline science for policymakers to use when making regulatory and land-use decisions.

EPA's Characterize the Watershed
Thurston County's Watershed Characterization Studies
Department of Ecology's Watershed Characterization and Land Use Planning
Department of Ecology's Puget Sound Characterization Project

Benthic Index of Biotic Integrity (B-IBI)

King County's ten metrics, known as the Benthic Index of Biotic Integrity, drives their monitoring and sampling efforts. By measuring these metrics, King County is able to use a score-card system to rank the health of their streams. This system allows for very different streams to be compared to each other and ranked according to their ecological health.

Raise the Grade

Pierce County's Raise the Grade project tracks and reports the water quality of streams and lakes in an annual Water Report Card. The goal of the Raise the Grade project is to improve water quality in streams and lakes with low grades.

Guidance for Developing Watershed Plans

The EPA's Handbook for Developing Watershed Plans to Restore and Protect our Waters.

The EPA's Quick Guide to Developing Watershed Plans to Restore and Protect of Waters (pdf)