Although estuaries cover only a small area, the essential ecological functions they deliver make them hugely important. They provide habitat for salmon transitioning to salt water as well as a food-rich environment that supports rapid growth of juvenile salmon prior to ocean entry. They provide key habitat for a broad range of fish and wildlife, including many economically important marine species and species of concern, such as black brant and sturgeon. They support other important social and ecosystem services such as flood control, water quality, carbon sequestration, and coastal food web support. 

The land-sea interface found in estuaries is one of the most ecologically rich and complex habitats on earth

People use estuaries in a variety of ways including agriculture, recreation, and transportation. However, 150 years of increasing human use have taken a toll on our estuaries, resulting in substantial loss of estuary habitats. Tidal wetland losses average around 70% for tidal marsh and over 90% for forested and shrub tidal swamps, leaving only a fraction of the high quality tidal wetlands that once provided the valued services listed above. 

 

Threats to estuaries include reduced habitat, tidal and floodplain disconnection and altered circulation, altered sediment regime, degraded sediment quality, degraded water quality, and climate change impacts (e.g. change in timing and distribution of rainfall, increased storm surges and intensity, and sea level rise). Changes in any of these key biophysical factors could lead to loss of estuarine function over time.