West Coast Estuaries Explorer

Estuaries are essential

to the health of coastal ecosystems

These highly dynamic systems, where rivers meet the ocean, provide many important ecosystem services. They provide essential habitat for a wide range of species, including fish, shellfish, shrimp, and crabs. Estuaries have also been significantly altered and degraded by human activities. Many along the West Coast are in poor condition or have lost significant habitat.

This viewer allows you explore estuaries along the coastline of Washington, Oregon, and California. Learn more about estuaries and their role in providing habitat for key species. Get involved to help restore these important ecosystems.

Compare estuaries

Compare and select estuaries based on type, size, and more.

Explore estuaries

Explore estuaries along the West Coast and learn more about them.

Learn more about estuaries...

The West Coast Estuaries Explorer

This application enables you to compare  estuaries to each other along the coastlines of Washington, Oregon, and California. You can combine dynamic filters and an interactive map to find specific estuary types you are interested in, such as large river delta estuaries which often have extensive diking; small, riverine estuaries that are at the lowest risk to fish habitat degradation; or estuaries contain species that interest you. Only want to compare estuaries in a specific area? Simply zoom the map in to that area, and the filters automatically update to show you the number of estuaries in that area that meet different conditions.

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You can also explore estuaries in more detail to find a specific estuary by name or location.

Click on an estuary in the map for more detailed information.

Estuary data were provided by the Pacific Marine & Estuarine Fish Habitat Partnership and the National Fish Habitat Partnership.

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Where a river meets the ocean

Estuaries and nearshore habitats are ranked among the world’s most productive ecosystems, providing social, ecological, cultural and economic benefits as well as a full array of ecosystem services. The constantly changing water chemistry, water level, and sedimentation creates unique challenges and opportunities for the organisms that make their homes in estuaries.

The Pacific Marine & Estuarine Fish Habitat Partnership (PMEP) mapped the current and historic extent of estuaries using models of extreme high water levels and high resolution elevation information. This allowed PMEP to determine areas that are inundated by the highest annual tides. PMEP then used the National Wetland Inventory, local knowledge, and other information to refine these boundaries. These estuary boundaries encompass all tidal wetlands, and they extend from the ocean to the head of the tide, including the freshwater tidal zone.

PMEP mapped habitats within the estuary boundaries based on the dominant vegetation type for a given area, using information from the National Wetlands Inventory and NOAA's Coastal Change Analysis Program. These habitat types are based on the Coastal and Marine Ecological Classification Standard.

For more information and data downloads, please click here.  You can explore these data interactively and overlay with many additional spatial data layers using the North Pacific Landscape Conservation Cooperative's Conservation Planning Atlas. You can also explore these data interactively with additional information about tidal wetland loss and restoration projects using the PMEP West Coast Estuary Viewer.

Estuaries provide essential habitat

Thousands of species of birds, mammals, fish and other wildlife depend on estuarine habitats as places to live, feed and reproduce. Many marine organisms, including most commercially-important species of fish, depend on estuaries at some point during their development.

In 2014, The Pacific Marine & Estuarine Fish Habitat Partnership assessed the nursery habitat potential for 15 ecologically and economically important fish and invertebrate species within Nursery Functions of U.S. West Coast Estuaries: The State of Knowledge for Juveniles of Focal Invertebrate and Fish Species.

These species were selected to encompass the diversity of life histories, habitat use, and ecological roles of species found in estuaries along the West Coast. This assessment compiled information on the presence of juveniles or the species in general within many estuaries along the West Coast. However, the estuary boundaries have been refined since that time, which means that species were assessed for somewhat different boundaries than those shown in this tool. Some records were based on large estuary systems that have since been mapped as smaller units. Not all estuaries were inventoried for species, so the absence of information about a species in a given estuary cannot be taken to indicate that the species is indeed absent from that estuary.

Estuaries are under threat

Estuaries and nearshore marine environments have been significantly altered due to human development activities. Projected increases in human population and activities in and around estuaries and nearshore areas, including watersheds, threaten the future of these important habitats. In addition, new stressors are emerging due to climate change, including ocean acidification, rising sea surface temperatures, increased storm intensities and extreme wave heights, rising sea levels, expanded hypoxic zones, and changes in sediment transport.

Vegetated tidal wetland loss:

Many areas of vegetated tidal wetlands have been lost to agriculture, development, and other land use changes. PMEP recently assessed vegetated tidal wetland loss by comparing the current extent of tidal wetlands in the National Wetland Inventory (NWI) to the historical estuary extent shown in this tool. Open water and aquatic vegetated areas were excluded from the analysis. This approach worked best for larger estuaries. Changes in estuary topography due to fill, outdated information from the NWI, and incomplete information on restored tidal wetlands may result in errors in these estimates of tidal wetland loss.

Where information is available, this assessment includes details about vegetated tidal wetlands that have been restored.

For more information about tidal loss and restoration, please see the assessment overview page.

Risk of fish habitat degradation:

In 2015 the National Fish Habitat Partnership assessed the status of fish habitats across the United States. This assessment analyzed disturbance factors that impact the quality of fish habitat, including:

  • River discharge: flow magnitude, duration of pulses, and density of dams
  • Pollution: density of point solution sites, including Superfind sites and mines
  • Eutrophication (excess nutrients in water): measures of chlorophyl content in the water, algae blooms, dissolved oxygen, and nutrient levels
  • Land cover: percent cover and trends of urban, agriculture, and wetland land cover

These factors were combined to create an overall index that shows risk to fish habitat degradation. Not all factors could be assessed for all estuaries; in this case at least three of the four factors were used.

For more information about this assessment, please see the 2015 Report.

Pacific Marine & Estuarine Fish Habitat Partnership

The Pacific Marine & Estuarine Fish Habitat Partnership (PMEP) works with partners to protect, enhance, and restore ecological processes and habitats within estuaries and nearshore marine environments. PMEP focuses on enhancing juvenile fish habitat, water quality, and water quantity in nearshore marine and estuary habitats, and also on connectivity between tidal and nearshore marine areas. These efforts prioritize healthy native fish communities and sustainable human uses that depend on them.

To get involved and find out more about PMEP, available funding opportunities, and projects supported by PMEP, please click here.

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North Pacific Landscape Conservation Cooperative

The North Pacific Landscape Conservation Cooperative (NPLCC) collaborated with many partners to put science to work toward more effective, landscape-level conservation. The NPLCC prioritized identification and sharing of information about natural resources throughout the region.

To access and collaborate around geospatial data within the NPLCC region, please visit the NPLCC Conservation Planning Atlas.

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This application was created by the Conservation Biology Institute  (CBI) in partnership with the Pacific Marine & Estuarine Fish Habitat Partnership and with financial support from the  North Pacific Landscape Conservation Cooperative and National Oceanic and Atmpospheric Administration - Office of Habitat Conservation. CBI provides science and software development to support the conservation of biodiversity.

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