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Update on Wetland Buffers: The State of the Science

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Update on Wetland Buffers: The State of the Science (Ecology Publication #13-06-011, October 2013). All the comments received during the public comment period and our responses were published in a separate document (Responses to Comments).

How does this update affect Ecology's guidance on buffers for local regulations?

This update does not address how this new information can be incorporated into critical areas ordinances.

Many local jurisdictions have included language on buffers in their critical areas ordinances based on Ecology's buffer guidance that was released in April 2005 (Appendices 8-C and 8-D of Wetlands in Washington State – Volume 2: Guidance for Protecting and Managing Wetlands). For the 2015-2019 critical areas ordinance update cycle, Ecology is not proposing any changes to the buffer widths recommended in the 2005 guidance.

How do the 2014 updates to the Washington State Wetland Rating System affect Ecology's guidance on buffers?

June 2014 webinar on the 2014 rating system updates

On June 3, 2014, Ecology wetland staff hosted a one-hour webinar on the updates. Information about integrating the rating system updates into Critical Areas Ordinance (CAO) updates was provided.

> View Presentation only (PDF)
> Listen to Recorded Audio version (YouTube)

In 2014, Ecology is updating the Washington State Wetland Rating Systems for eastern and western Washington. For more information on the updates and how they affect Ecology's guidance on buffers, please see this web page: 2014 Updates to the Washington State Wetland Rating Systems. Also see the box at right.


In 2005 the Department of Ecology published a synthesis of scientific information available on freshwater wetlands, their functions, and their management (Wetlands in Washington - Volume 1: A Synthesis of the Science, Publication #05-06-006). The purpose of the synthesis was to provide local governments in the state with the best available science (BAS) when managing their wetland resources. Using BAS in making decisions was mandated by the 1995 amendment to the Growth Management Act (Revised Code of Washington (RCW) 36.70A.172[1]).

Our scientific knowledge is continually increasing and changing and we recognized that the synthesis would need periodic updates. Much of the information presented is still valid, but the research in the last decade has provided new data to expand and clarify many of the conclusions made in the original synthesis. This is especially true for the information on the role of buffers in protecting wetland functions.

Several jurisdictions, including Island and San Juan counties, have developed their own syntheses of scientific research based on some of the more recent information on buffers. These syntheses focused on the wetlands found within their jurisdiction and the information may be limited relative to other areas in the state. The Department of Ecology is expanding on these efforts. The goal is to provide updated information on wetland buffers that can be applied statewide. The objective is to synthesize the information on buffers that was published between 2003 and the winter of 2012. The focus of this update is on wetland buffers, since buffers are one of the most common elements of wetland regulations in Critical Area Ordinances (CAO), and they are consistently the part of a CAO of most interest and concern to the public. Limited resources prevent us from expanding our review and update to other issues at this time.

This update revisits the conclusions and key points concerning wetland buffers made in the 2005 synthesis of the science for wetlands. Each conclusion is reviewed with respect to any new information that was published between 2003 and 2012. If the conclusion is still valid, any new references supporting it are noted. If the conclusion needs to be expanded or modified, then revised conclusions are presented based on the new information. In reviewing the recent information we also found that some of the studies address issues that were not commonly discussed in the past. New conclusions that can be made from this information are presented as updates of the old conclusions.

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