The San Francisco Bay is the largest estuary in the western United States, encompassing 1,600 square miles. Wetlands make up 628,549 acres of the estuary, according to the US Fish and Wildlife Service National Wetland Inventory. Over half (385,755 acres) are farmed, but the rest remain suitable habitat for a diversity of life. San Francisco Bay is a stop for nearly half of the waterfowl and shorebirds migrating along the Pacific Flyway. Endangered species, such as the California clapper rail, California least tern, and the salt marsh harvest mouse, also call the wetlands home.
The salt marsh that currently fringes the Bay is only a small fragment of its original size. Eighty-five percent of the original salt marshes has been destroyed because of development. When the first inhabitants of San Francisco Bay, the Ohlone, settled the area, they harvested the salt and used the natural materials in the marsh. The arrival of the Spanish missionaries virtually wiped out the native population and paved the way for more Europeans to come. The real boom time for San Francisco was during the Gold Rush, when the population exploded. The Bay, however, suffered as a result of the sediments and mercury from mining that entered the tributaries.
As the city grew, the Bay was filled in without any protest until the nineteen-sixties when a grassroots environmental movement began to stop development projects. Eventually people realized that stopping the projects was not enough, and they also needed to restore the wetlands that had been degraded, like those that were used for salt evaportation ponds. It is only recently that people have begun to acknowledge the value in wetlands.
The wetlands serve the nearby large urban area by improving water quality, controlling floods, providing fish and wildlife habitat, recharging groundwater, creating recreational space, and stabilizing shoreline. However, they face the challenges presented by modern urbanization: invasive species, shoreline development, runoff and pollution, freshwater diversion, waste disposal, and agriculture.
Natural History
| Location | Geology | Climate | Hydrology |
| Vegetation | Wildlife | Ecology |
Human Interactions
| Indigenous Use | History Since European Settlement | Current Issues |
| Current Condition | Future |
References
About the Author
Amy Niemczura
Last Updated April 6, 2007
NR 260: Wetland Ecology
Rubenstein School of the Environment and Natural Resources
University of Vermont