Puget Sound Main Basin

Map of regional water masses and subareas of Puget SoundThe main basin of Puget Sound runs from the Tacoma Narrows to the waters between Point Wilson, on the Olympic Peninsula, and Whidbey Island.  There are sills at the northern and southern ends, and depths in the central part range from 100 to 140 meters. The five sub-basins within this part of the Sound all reach depths below 150 meters, with the deepest being 290 meters west of Port Madison. The basin includes Elliott Bay and Commencement Bay, which receive fresh water from the Duwamish-Green river system and the Puyallup River, respectively.

The Skagit River provides around 30 percent of the freshwater flow into the main basin, which is stratified in summer but mixes well in winter due to cool temperatures and increased wind. Decadal climate regimes influence the circulation patterns in the basin. During cool periods, the strongest currents flow from the Strait of Juan de Fuca at a medium depth, but when warmer, drier weather dominates, currents tend to be strongest at the bottom of the basin. Dominant vegetation is green algae and eelgrass, but overall vegetation is sparse. Only 8 percent of the shoreline has continuous eelgrass beds, with a patchy distribution over an additional 40 percent.



A baseline assessment report cover page

A baseline assessment of priority invasive species in the Puget Sound Basin

The baseline assessment summarizes the status and trends of 15 priority invasive species, as identified by the Washington Invasive Species Council, within the Puget Sound Basin.

Book cover for The Salish Sea: Jewel of the Pacific Northwest

New book focuses on the natural history of the Salish Sea

The Salish Sea: Jewel of the Pacific Northwest brings together more than 230 extraordinary images of the Salish Sea. But don't call it a coffee table book. Its lush photos are backed by a serious scientific perspective on this complex and fragile ecosystem.

Seattle's central waterfront at sunset. Photo: Michael Matti (CC BY-NC 2.0) https://www.flickr.com/photos/michaelmattiphotography/9090323308/

Brighter future for salmon at downtown seawall

The decaying seawall along Seattle’s waterfront is providing scientists with an opportunity to improve long-lost habitat for migrating salmon. It could also show the way for habitat enhancements to crumbling infrastructure worldwide. One University of Washington researcher describes the project.

Canary rockfish. Photo by Tippy Jackson, courtesy of NOAA.

Proposed designation of critical habitat for the distinct population segments of Yelloweye Rockfish, Canary Rockfish, and Bocaccio

The National Marine Fisheries Service has released a Draft Biological Report proposing designation of critical habitat for yelloweye rockfish, canary rockfish, and bocaccio in the Salish Sea. Download the full report and supporting data.

Screenshot of 2013 Health of the Salish Sea Ecosystem Report

Report: 2013 Health of the Salish Sea Ecosystem Report

The 2013 Health of the Salish Sea Ecosystem Report was prepared jointly by the U.S. Environmental Protection Agency and Environment Canada. View the complete report, or read the Executive Summary below.


Western Grebe; image by mikebaird, courtesy of Encyclopedia of Life

Paper: Citizen science reveals an extensive shift in the winter distribution of migratory Western Grebes

A June 19, 2013 paper in the journal PLoS ONE hypothesizes that regional declines in Western Grebe populations may be related to decreasing numbers of forage fish. Using citizen science data from 36 years of bird counts, researchers were able to look at population trends up and down the entire West Coast, finding that abundance of grebes decreased in the Salish Sea but increased in southern California. North American population declined by 52% overall.

Block seine fishing. Image courtesy of WDFW.

Report: Economic analysis of the non-treaty commercial and recreational fisheries in Washington State

This report, published in 2008 by the Washington Department of Fish and Wildlife, summarizes the economic importance of Washington fisheries using data from 2006. The report's Executive Summary is reprinted below, followed by summaries of data specific to Puget Sound.

Fringed Myotis. Photo © Merlin D. Tuttle, Bat Conservation International, www.batcon.org

Report: Washington State Bat Conservation Plan

The Washington Department of Fish and Wildlife recently released a Bat Conservation Plan for the 15 species of bats found in Washington State. All but four of these species occur within the greater Puget Sound watershed1, including:


Puget Sound Chinook Salmon recovery: a framework for the development of monitoring and adaptive management plans

The Puget Sound Recovery Implementation Technical Team has released a draft of a NOAA technical memorandum describing frameworks for adaptive management and monitoring of Chinook salmon in Puget Sound. Download the report.

MoSSea snapshot of sea surface temperature over the full model domain around May 15, 2006; image courtesy of PRISM

Water quality model development and application in Puget Sound and Georgia Basin

A recent summary includes information compiled in Winter 2013 by the modeling workgroup of the Puget Sound Ecosystem Monitoring Program (PSEMP). It describes several ecosystem modeling efforts in the region.

Salish Sea map my Norm Maher. Courtesy of the SeaDoc Society.

The Salish Sea

The Salish Sea extends across the U.S.-Canada border, and includes the combined waters of the Strait of Georgia, the Strait of Juan de Fuca, Puget Sound Basin and the San Juan Islands (see map).

The name Salish Sea was proposed by Bert Webber in 1989 to reflect the entire cross-border ecosystem. Both Washington State and British Columbia voted to officially recognize the name in late 2009. The name honors the Coast Salish people, who were the first to live in the region.

Northern Sea Otter. Photo: Alaska Department of Fish and Game

Species of concern in the Salish Sea

The Encyclopedia of Puget Sound species library now includes a list of species of concern in the Salish Sea watershed. The list was created by Joe Gaydos and Nicholas Brown of the SeaDoc Society, and was released as a paper presented as part of the Proceedings of the 2011 Salish Sea Ecosystem Conference in Vancouver, BC.


Puget Sound watershed hydrologic units

There are many ways of defining the boundaries of the Puget Sound watershed. Hydrologic unit codes (HUCs) are nationally standardized divisions that are often used by conservation agencies and national organizations.

Interesection of NW GAP Hydrological Units and Puget Sound WRIAs

Puget Sound terrestrial vertebrates

The Encyclopedia of Puget Sound, in cooperation with the USGS, has developed a list of terrestrial vertebrates occurring within the Puget Sound basin.

Adult female Rana aurora during fall migration of 2005 in Puget Sound (Hayes, Marc 2005).

Red-legged frogs in the Puget Sound watershed

The Northern Red-legged Frog is described here relative to its local behavior, habitat, threats and morphology.