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Mitigation Resources

Characterizing Wetland Functions and Values | Choosing a Mitigation Site | Understanding Mitigation Options
Focus Sheets & Frequently Asked Questions




  • 2006 wetland mitigation interagency guidance - a comprehensive two-part interagency document providing guidance on wetland mitigation. Part 1 provides detailed guidance on the agencies' policies on wetland mitigation. Part 2 provides technical information on preparing plans for compensatory mitigation.

Better mitigation through better science and adequate buffers and ratios.

  • Best Available Science for Wetlands -  a two-volume document: Volume 1 is a synthesis of the science regarding freshwater wetlands and Volume 2 translates the science synthesized in Volume 1 into guidance for local governments protecting and managing wetlands.
  • Guidance for Local Governments on Developing a Wetland Protection Program - guidance for local governments that are in the process of updating their critical areas ordinances (CAOs). This document describes the important topics that should be addressed in the wetlands section of a CAO. It includes recommendations for wetland protection based on best available science (BAS). The guidance includes an appendix that transcribes these recommendations into a format that is similar to that found in many local CAOs.

Characterizing Wetland Functions and Values

Better mitigation through a better understanding of wetland functions and values.

  • Washington State Wetland Rating Systems - the wetland rating systems were designed to differentiate between wetlands in western and eastern Washington. They categorize wetlands into four categories based on their sensitivity to disturbance, their rarity, our ability to replace them, and the functions they provide.
  • Calculating Credits and Debits for Compensatory Mitigation in Wetlands - a tool for calculating when a proposed wetland mitigation project adequately replaces the functions and values lost when wetlands are impacted. It is also known as the Credit/Debit Method.

Choosing a Mitigation Site

Better mitigation through improved site selection.

Understanding Mitigation Options

Better mitigation through a comprehensive range of mitigation options.

Focus Sheets & Frequently Asked Questions


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