Eelgrass/Macroalgae Habitat Interim Survey Guidelines

Category: Guidelines

Published: June 16, 2008

Pages: 6

WDFW has developed revised survey guidelines for eelgrass and macroalgae habitat to improve protection of these important habitats in Puget Sound and coastal waters. Guidelines for both preliminary and advanced surveys are contained in the revised protocols to facilitate evaluation of potential impacts to these habitats at project sites with various conditions. Statistical considerations are an integral part of the advanced surveys and a sample size calculator has been included to aid in determining the appropriate number of samples to be taken at a particular site.


Under the Washington Administrative Code (WAC), eelgrass and macroalgae are defined as saltwater habitats of special concern (WACs 220-110-250 (3)(a, b)). In administering the Hydraulic Project Approval (HPA) process, the Washington Department of Fish and Wildlife (WDFW) requires proponents for projects to: 1) avoid impacting eelgrass and macroalgae, 2) minimize unavoidable impacts, and 3) mitigate for any impacts.

Mitigation for the loss of eelgrass typically entails providing eelgrass enhancement away from the project footprint. Because establishment of new eelgrass for mitigation is often unsuccessful, project proponents need to address this uncertainty by increasing the scope of their mitigation effort, such as planting an area larger than the project impact footprint. For macroalgae mitigation measures, the WDFW Area Habitat Biologist (AHB) shall be consulted.

In known or suspected eelgrass areas, proponents shall survey to delineate the spatial extent of eelgrass and macroalgae presence in the project area. If the project cannot be moved or redesigned to avoid direct eelgrass and macroalgae impacts, surveys are required for quantifying potential impacts. Surveys shall be conducted by divers/biologists who are qualified to identify the predominant eelgrass and macroalgae species in the project area. Deviations from the survey guidelines shall be approved by the AHB prior to conducting eelgrass or macroalgae surveys. Survey results and interpretation will be subject to WDFW approval.