The San Francisco Bay Estuary
The Sacramento River begins its flow to the sea near Mount Shasta in the Cascade Mountain Range. Three hundred miles away in the snows of the Sierra Nevada, another great river, the San Joaquin, has its beginning. Until they were dammed and diverted, these two rivers carried about half of the precipitation that fell on California into the Delta where the rivers meet, about 40 miles northeast of San Francisco.
The water then flows into Suisun Bay, through the Carquinez Strait into San Pablo Bay, and finally into San Francisco Bay itself. These three bays and five others--Honker, Richardson, San Rafael, San Leandro, and Grizzly--make up the estuary known as San Francisco Bay. Like all estuaries, San Francisco Bay is a wide river mouth flooded by the sea which flows on ocean tides through the Golden Gate. The mixture of salt and fresh water is the foundation of the biological richness of estuaries. San Francisco Bay is the largest estuary on the Pacific Coast making it one of the world's great natural resources.
The marshes and mudflats along the shoreline of the Bay are sources of food and shelter for a wide variety of fish and wildlife. Hundreds of thousands of birds migrating between the Arctic and South America--fully 50 percent of the birds using the Pacific flyway--rest and feed on the Bay. Over a million birds visit the Bay each year. The Suisun Marsh, which alone comprises almost ten percent of the remaining natural wetlands in California, is a particularly valuable habitat and is critically important to waterfowl during droughts. The Bay supports over 130 species of fish, including salmon and other anadromous fish, which spend most of their lives in the ocean but return to fresh water to reproduce. Harbor seals, gulls, sea bass, geese, and thousands of other species of fish, plants, mammals, reptiles, and birds thrive in the San Francisco Bay estuary.
San Francisco Bay makes many contributions to human welfare. The fish, whether caught in the Bay or harvested from the ocean after spending part of their lives in the Bay, provide food and recreation for some people and an economic livelihood for others. The salt harvested from the Bay waters is an important raw material for industry.
The vast enclosure of San Francisco Bay with its single narrow opening provides one of the world's great natural harbors. The Bay is the fifth largest U.S. port in crude oil handling and the fourth largest container port. The goods shipped to, from, and through Bay ports add to the Nation's economic well-being and cultural richness. The Bay has also served as an important base for America's military forces.
The Bay is essential to the many shorefront industries that receive raw materials or produce goods moved by ship, and the Bay is home to oil refineries and a variety of industries. Planes using airports along the Bay shoreline can arrive and depart over water, thus reducing the noise and danger to those on the ground.
Beyond its direct contribution to commerce, defense, transportation, and economic prosperity, San Francisco Bay plays other roles that are both more subtle and more valued. The consistent temperature of the Bay water cools the surrounding region in the summer and warms it in the winter, making the Bay area climate among the world's most enjoyable. The fish and wildlife that abound in the Bay and its marshes delight fishermen, hunters, and anyone out for a casual stroll. The Bay's thousand miles of shoreline provide stunning settings for diverse communities and offer spectacular views of the Bay's scenic splendors. The Bay's unparalleled beauty is the basis of the region's tourist industry which attracts millions of visitors from around the world. This beauty is also the underpinning of an elusive concept called quality of life, which is of such richness that the Bay region is one of the country's most desirable places to live.
For more information on the bay, click here for links to other bay-related sites.