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Seagrass on the West Coast

Seagrasses are one of the only flowering plants, or angiosperms, that can grow in a marine environment.

Seagrasses are one of the only flowering plants, or angiosperms, that can grow in a marine environment. These plants support a diversity of life and can form extensive beds in shallow, protected, estuarine, or other nearshore environments. Two common seagrasses that occur on the West Coast are eelgrass (genus Zostera) and surfgrass (genus Phyllospadix), with eelgrass being the most prevalent and occurring in Washington, Oregon, and California.

Eelgrass (Zostera marina) provides many biological and ecosystem services, including shelter for juvenile fishes, shoreline stabilization, and water quality improvements. Eelgrass builds complex habitat and is an important foraging area for multiple species, including fish. It grows in quiet bays and harbors as well as open coast regions. Because of its location throughout inshore areas, eelgrass is subject to adverse effects from development, reductions in water quality, and vessel activity.

NOAA Fisheries works to conserve eelgrass through a variety of approaches including development of policy to avoid, minimize or offset impacts to eelgrass, facilitation of research efforts, and mapping of the resource. Along the West Coast, the Pacific Fishery Management Council identified seagrasses, including Zostera marina, as a Habitat Areas of Particular Concern (HAPC) for Pacific Coast groundfish. Seagrasses are also identified as part of the submerged aquatic vegetation HAPC for Pacific Coast salmon.

Below are links to policies, tools, and data relevant to NOAA Fisheries eelgrass conservation efforts on the West Coast:


California Eelgrass Mitigation Policy – Established an appropriate eelgrass survey protocol to evaluate impacts from coastal development projects and mitigation requirements to ensure no net loss of habitat function. Please note that this policy applies only to the state of California and not the entire west coast.

Turbidity Best Management Practices – Presents guidelines to limit the impacts of turbidity based on various project features.

San Francisco Bay Light Monitoring Protocol – Eelgrass is often light-limited and even slight reductions may be sufficient to cause a reduction in habitat. These guidelines were developed to promote appropriate light monitoring for projects in San Francisco Bay.

Overwater Structures Decision Tree – This tool was developed to help project applicants navigate the essential fish habitat review process for: (1) small boat dock projects; (2) multi-family docks, marinas, and similar overwater structures; and (3) large, industrial overwater structures.

EcoAtlas – This website contains a spatial depiction of eelgrass distribution throughout California. In addition, several project specific maps and surveys are available for viewing as well. Please note that the data for this website are not comprehensive and therefore do not contain the absolute distribution of eelgrass throughout California.


U.S. Army Corps of Engineers Eelgrass Monitoring Protocol – This monitoring approach has been implemented in the northwest.

Eelgrass/Macroalgae Habitat Interim Survey Guidelines – These survey guidelines from the Washington Department of Fish and Wildlife have been implemented in the northwest.

West Coast Region-wide

NOAA Fisheries facilitates the collection and dissemination of eelgrass spatial data for the purposes of research, project planning, and general education. The Geographic Information Systems (GIS) shapefiles are available on the EcoAtlas webpage, under Eelgrass Aquatic Resources.

Spatial Data

Eelgrass distribution may change over time as a result of variable growth conditions. While distribution maps may require frequent updating, historic data may identify areas of persistent growth and give an idea of the maximum potential extent within a system. NOAA Fisheries has been facilitating the collection of data on eelgrass distribution because it assists project managers in avoiding, minimizing or offsetting the impacts of coastal development projects, supports the design of research projects, and promotes awareness to the public. These data are available on the EcoAtlas webpage, under Eelgrass Aquatic Resources. Currently there is only spatial data available for California.

Please send additional inquiries regarding these data to

Last updated by West Coast Regional Office on May 19, 2022