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About the Estuary
What is an Estuary?
Where the river meets the sea…
An estuary is a body of water at the lower end of a river (or rivers) connected to the ocean and semi-enclosed by land. In an estuary, sea water is diluted by fresh water from the land. Estuaries come in all shapes and sizes, and are called many different names -- bays, lagoons, harbors, inlets, or sounds. The San Francisco Bay-Delta Estuary connects the San Joaquin and Sacramento Rivers to the Pacific Ocean and includes both the Delta and San Francisco Bay.
The San Francisco Bay-Delta Estuary
An estuary of national significance…
An estuary of national significance and an international treasure, the San Francisco Bay-Delta Estuary is the largest estuary on the West Coast of the United States. It provides vital resources for humans and wildlife. The Estuary System encompasses roughly 1,600 square miles, provides drinking water to more than 23 million Californians (two-thirds of the state’s population) and irrigates 4.5 million acres of farmland. Millions of tons of agricultural commodities and commercial goods are shipped via its waterways.
Vital Habitat
The Estuary provides vital habitat to wildlife, including endangered species such as the California Clapper Rail and the Salt Marsh Harvest Mouse. More than 200 species of birds, 130 species of fish, 52 species of mammals and 22 species of amphibians and reptiles are found in the Estuary. Two-thirds of the state’s salmon pass through the Bay and Delta, as do nearly half of the waterfowl and shorebirds migrating along the Pacific Flyway.
The Watershed
A watershed is an area of land that drains all of its water—rivers and streams, rainfall and snowmelt, and urban runoff—to one specific water body. It extends from a point of high elevation, such as a ridgeline, down to a low point where the water flows into a creek, river, bay, ocean, or other waterbody. Watersheds come in all sizes, from large river systems to small creeks, and they cross county, state, and national boundaries. Wherever you are, you live, work, and play in a watershed.
The vast watershed for the San Francisco Bay-Delta Estuary encompasses roughly 60,000 square miles and drains more than 40 percent of California’s lands. Mountain streams surrounding California's Central Valley feed into the San Joaquin and Sacramento Rivers, which feed into the Bay-Delta Estuary.
Climate Change and Sea Level Rise
Global climate change is expected to significantly impact the San Francisco Bay-Delta Estuary, bringing rising sea-levels, changes to water chemistry and salinity, and changes in the species of fish, wildlife, bird and organisms that inhabitat the Estuary.
The California Environmental Protection Agency’s “Climate Action Team Report to the Governor and the Legislature,” evaluated three scenarios for reducing the amounts of greenhouse gases released into the atmosphere over the next century. Depending on whether and how much these emissions can be brought under control, the report projects that by 2100 average temperatures in California will rise between 3 and 10.5 degrees Fahrenheit. Depending which end of the range of projected temperature increases comes about, the California Climate Action Team found that water levels in San Francisco Bay could rise an additional five inches to three feet, or nearly one meter by the end of this century.
The Estuary Project’s Comprehensive Conservation and Management Plan includes numerous actions relating to climate change. One of the Estuary Project’s partners, the Bay Conservation and Development Commission has developed a Climate Change Strategy.