An estuary is a geographic concept that describes where freshwater enters the sea, creating a complex landscape of mixed fresh and salt water. The exact boundary of the estuary depends on your interests in defining the boundary. From a national perspective, the whole Salish Sea could be considered an estuary. Within the greater Salish Sea estuary, there are a number of sub-estuaries, from large river deltas to the many embayments often associated with stream mouths.
- File:Cereghino 2014 sub-estuary inventory in puget sound.pdf describes data available to inventory Puget Sound sub-estuaries, and makes a case that a thorough inventory and characterization has not been completed.
- The PSNERP geodatabase has shoreform classification that includes stream mouths and some estuarine land forms, including historical and current coastal wetlands. Included in those data are analyses from Cereghino et al 2012 that describe the relative size of coastal inlets and the size of the watersheds flowing into them.
- McBride et al 2009 presents an alternate shoreline classification with more resolute assessment of estuary landforms.
- Redmond et al 2005 provides an analysis of 'pocket estuaries' for Salmon Recovery planning.
- Most of the Puget Sound basin drains through 16 River Deltas identified by Simenstad et al 2011 puget sound nearshore change analysis.
- Nearshore Salmon Recovery Planning is often focused on estuaries, because the high productivity shallow waters, and the flow of insects and debris out of streams and rivers, and the association of young fish with their natal streams all result in estuaries being important places for salmonids, particularly Chinook and chum salmon, which depend on estuarine rearing.
- Olympia Oyster Restoration often takes advantage of freshwater seeps and streams, which can discourage natural predators.