This indicator measures the amount (acres and percent) of estuarine surface area in functional condition in Puget Sound’s 16 large river deltas. Estuary function is measured by the extent of connected tidal wetlands. Functional estuaries provide many ecosystem services and are critical to the recovery of the region’s salmon populations.

• Puget Sound contains 16 large river deltas, covering approximately 100,200 acres. Within these boundaries, 76,500 acres are mapped as current or potential tidal wetland habitat (excludes areas that are developed or outside of tidal extent). 28 percent of the wetland habitat has unrestricted tidal connectivity (all surrounding and downstream wetlands are open to tidal flooding). Nine percent of the wetland area is tidally influenced habitat, but connectivity is either partially or significantly restricted. 61 percent of Puget Sound’s delta wetland area has been completely blocked from tidal connectivity.
• Tidal restrictions, such as dikes/levees, roads, railways, and armored banks, restrict or prohibit tidal connectivity and wetland function. Cramer Fish Sciences mapped over 760 miles of restrictions that completely block tidal connectivity in Puget Sound’s large river deltas. This includes approximately 455 miles of roads and railways, 220 miles of dikes/levees, and 87 miles of armored banks.
• Removing tidal restrictions and improving the connectivity of tidal restriction features represent the best opportunities to increase functional and accessible tidal wetland habitat in Puget Sound.
• Since 2006, restoration activities have reintroduced or improved tidal connectivity to 3,420 acres in Puget Sound’s large river deltas. Most restoration occurred in the Snohomish, Nisqually, Skagit, Stillaguamish, and Skokomish deltas.
• A change analysis comparing tidal wetland connectivity between 2011 and 2020, showed gains in estuary function from restoration. The analysis did not identify any wetland loss or new restrictions to tidal connectivity over the 10-year period. While this points to improving progress in estuary function, extensive areas of historical habitat remain lost or degraded in many Puget Sound deltas.
• The extent and composition of functional estuary area varies by Puget Sound delta. Please see the Interpretation of Results section for more detailed summaries.