Places We Protect

Port Susan Bay Preserve


A father and his two sons turn over a rock on the beach of Barnum point to discover what wonders might be hidden beneath.
Exploring Port Susan Bay: A father and his two sons turn over a rock on the beach of Barnum point to discover what wonders might be hidden beneath. © Benj Drummond

A marshland home for fin and fowl.



Port Susan Bay holds some of the finest estuarine habitat in Puget Sound. Its marshes, vast mudflats and tidally influenced channels support hundreds of thousands of birds, several species of salmon, smelt, English sole and clams. Western sandpipers, dunlins and dowitchers swoop over the mudflats. Wrangel Island snow geese gather by the thousands in tidal marshes and on nearby farm fields. And hundreds of raptors, from peregrine falcons to short-eared owls, add to the drama.

The Stillaguamish River spills into the bay, mixing freshwater and saltwater to create extensive estuarine marshes that produce a vast quantity of decaying organic matter, which feeds the abundant invertebrate life in the tide flat sediments. These tiny creatures, in turn, feed the shorebirds and waterfowl that make Port Susan Bay and adjacent Skagit Bay important stops for migratory birds traveling along the Pacific Flyway

Download a factsheet on Port Susan Bay Preserve.

Other birding sites in the area that do not require prior permission:



Explore our work in this region


Interested in seeing the beauty of Port Susan Bay? Please contact the reception desk at the Seattle office, or (206) 436-6200 (hours Monday-Friday 9am-5pm) at least one week in advance to make your reservation. Visitors will be required to complete and submit a liability form prior to their visit. Forms can be submitted via email to or via mail to 74 Wall Street, Seattle, WA 98121.

Conservation Actions

The Conservancy owns the 4,122-acre Port Susan Bay Preserve, which encompasses much of the Stillaguamish River estuary. The property is managed in a way that benefits the vibrant estuary system and its salmon, birds and other wildlife.

The Conservancy also completed the Port Susan Bay Estuary Restoration Project to restore 150 acres of tidal marsh in the Stillaguamish River estuary. An outer dike was removed and an inner dike redesigned to provide greater protection for neighboring farmlands during floods, and improve the ability of fish caught in flood waters to return to the natural system.

Now, native tidal-wetlands that support estuary-dependent animals are in better condition, juvenile chinook salmon have access to restored rearing habitats, and the stronger connection between the river and tidal habitats in the northeastern portion of Port Susan Bay will improve the resilience of the bay and estuary to sea level rise. Healthier tidal wetlands mean more food in the system for salmon, Dungeness crab, gray whales...and people.

Conservation Context

The Port Susan Bay Preserve is part of a larger landscape that is important for both wildlife and people. A collaborative, non-regulatory Marine Stewardship Area has been proposed for the entire Port Susan Bay and nearby uplands. You can read more on the Snohomish County Marine Resources Committee website.