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Watershed Characterization and Land Use Planning

Land use planning and permit decisions are usually made using site scale information.  It is rare that these decisions are adequately informed by an understanding of ecosystem processes or watershed conditions. We believe one of the keys to making mitigation work is to move away from the narrow view of site-by-site piecemeal solutions, and towards a broader ecosystem or watershed scale view to achieve a more functional and resilient natural system. Watershed characterization is an approach for incorporating this understanding into the local government planning and permitting process.


  • Sustain and restore aquatic resources.
  • Establish a common approach to coordinate planning efforts.
  • Involve the community in developing a green infrastructure plan.
  • Promote the integration of the Growth Management Act (GMA) and Shoreline Management Act (SMA).
  • Support Shoreline Management Plan (SMP) updates by:
    • Establishing a framework for characterizing landscape processes and developing a restoration plan as required under the SMA.
    • Promoting "no net loss" of shoreline and wetland function.


  • Provides for the comprehensive long term protection of aquatic resources and maintenance of quality of life.
  • Guides future development (e.g. “green infrastructure” ) to:
    • Identify and avoid development patterns that cause problems difficult for a community to correct in the future.
    • Provide background information necessary for completing SMP and comprehensive plan updates, including critical areas ordinances.
    • Reduce total development costs.
  • Streamlines permitting because it can:
    • Provide a predictable permitting environment for developers.
    • Reduce permit review, project implementation and enforcement time.
    • Provide more local control and less state overview.
  • Provides flexibility to meet the needs of the community.

Watershed Characterization

In its most basic form, watershed characterization information can help identify areas that are:

  • priorities for acquisition (or protection via conservation easements),
  • more appropriate for restoration and/or mitigation/conservation banks,
  • less likely damaged by development impacts to ecosystem or watershed processes.

Where watershed characterization reveals major conflicts between ideal and actual land uses, planners and permit writers should acknowledge these conflicts and learn from these situations to reduce future siting conflicts. Local governments can and should use characterization information to support the development of local shoreline master plans and critical area ordinances.

Guidance and Examples

These examples demonstrate various applications of watershed characterization in land use planning, as well as Ecology’s guidance as it evolved over time. The most current methods are listed first, and earliest versions listed last.

Puget Sound


  • Guidance for Small Cities on Developing a Wetland Protection Program, January 2010
    Guidance for small cities and towns 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.
  • Critical Areas Ordinance Code Examples: Off-site mitigation language, March 2009 (PDF, 51KB)
    Examples from critical areas ordinances statewide, allowing for off-site mitigation.

Upper Chehalis Basin

South Lewis County

Clark County

Birch Bay

  • Presentation on A Watershed Based Management Plan for Birch Bay, April 2009 (PDF, 3.2MB)
  • Birch Bay Characterization and Watershed Planning Pilot Study, October 2007 (PDF, 8.9MB)
    The Birch Bay study was a collaborative effort by local, state, and federal agencies to create a comprehensive set of watershed management recommendations using integrated watershed characterization tools. The primary participants in the study were the Whatcom County Planning and Development Services Department, EPA, Ecology, WDFW, and the Partnership. The Birch Bay study provides preliminary recommendations for land use planning and resource management that will maintain—or preferably improve—the quality and condition of local wetland, stream, nearshore, and terrestrial resources in the Birch Bay watershed.

Snohomish Estuary Wetland Integration Plan

  • Salmon Overlay to the Snohomish Estuary Wetland Integration Plan, March 2001 (PDF, 8.9MB)
    The Salmon Overlay is a tool to aid jurisdictions in responding to ESA and developing an appropriate management plan for the estuary as a component of a basin wide (Water Resource Inventory Area [WRIA] 7) management strategy for recovery of listed species. Products and outcomes of the Salmon Overlay include the following:
    • A scientifically based Tidal Habitat Model that will characterize indicators of habitat functions within the study area specifically focusing on habitat for listed anadromous fish species.
    • An inventory, based on the Tidal Habitat Model, of the quality of habitats now available to listed species in the study area.
    • Identification of high-value habitats that should be preserved.
    • A listing and ranking of projects and opportunities for restoration/enhancement of habitat within the planning area.
    • A process for comparing potential development impacts within the urban growth areas (UGAs) of Everett, Marysville, and Mukilteo (part) with potential mitigation and restoration opportunities in the SEWIP planning area.
    • Recommended mitigation and restoration/enhancement policies for development.
  • Snohomish Estuary Wetland Integration Plan, April 1997 (PDF, 12MB)
    The Snohomish Estuary Wetland Integration Plan (SEWIP) is a proposal to integrate the wetland regulatory frameworks of federal, state and local agencies into one process on the basis of an agreed-upon plan. The products and outcomes of this effort are a scientifically based inventory of the functions and values of study area wetlands and a framework, agreed upon by all the regulatory agencies, for expediting review of development proposals through the federal, state, and local permit processes. It is intended to provide an alternative which, when applied, will provide substantial savings of time and costs associated with development in and around the estuary. It was adopted by reference in the city's Shoreline Master Program (SMP). The plan is comprised of five basic elements:
    • Inventory and assessment of wetland resource;
    • Identification of areas where development can occur;
    • Listing of enhancement and restoration sites and actions;
    • Wetland compensation policies and replacement ratios; and
    • Recommended management guidance.


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