Lecture+11-12-08+SF+Bay-+Morris - San Francisco Bay is a...

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Unformatted text preview: San Francisco Bay is a National Treasure The Bay enriches the lives of millions of residents and visitors from all over the world. The Bay not only shapes our weather, it also gives the Bay Area its very identity. Bay or Estuary? Estuary: A partially enclosed body of water where salt and fresh water meet and mix. San Francisco Bay Watershed An area of land that water flows over on it's way to a larger body of water 60,000 Square Miles of land drains into the San Francisco Bay! 40% of California The Bay was created by crustal subsidence associated with the San Andreas fault. During the last ice age when sea levels were lower, the ocean coastline was near the Farallon Islands, 25 miles further west than today. Rivers carved a path through the coast range to the Pacific Ocean, forming the Golden Gate. These geologic forces formed a biologically rich estuary that supported a wide range of wildlife, including grizzly bears, pronghorn antelope, tule elk, salmon and millions of waterfowl. Before the arrival of Europeans in the mid-1800s, the Bay was bordered with extensive salt marshes and mudflats ideal habitat for waterfowl and shorebirds. The native peoples were able to feed themselves quite easily from the bounty of the rich estuary and Bay wetlands. Today only 5 percent of the Bay's original mudflats and wetlands remain. The rest have been diked or filled and developed. In the 1870s and 80s, hydraulic gold mining in the Sierras washed huge amounts of debris downstream and into the Bay and Delta. Marshes were diked and drained for farms in the North Bay and Delta, and for salt ponds in the South Bay. Other marshes were filled in to expand cities. These activities reduced the total area of the Bay by more than onethird. The red regions on this map indicate areas diked off or filled in. A U.S. Army Corps of Engineers study showed that 60 percent of the remaining Bay was shallow enough to be filled for development, leaving only a narrow river for navigation. This 1959 depiction of that study in the Oakland Tribune ignited regional concern about the future of the Bay. Sylvia McLaughlin, Esther Gulick, and Kay Kerr (left to right) saw the Bay shrinking from their homes in the East Bay hills. When their appeals for help from other environmental groups were turned down, they mobilized friends and founded Save San Francisco Bay Association, the first U.S. organization of its kind. More than 20,000 members joined for $1 per year, and the "Save The Bay" movement grew rapidly. Wetlands: Wetlands are the Bay's lungs, needed to filter pollution, provide habitat for wildlife, and flood control for cities. These Caspian Terns are just some of the birds that use the San Francisco Bay for habitat. More than 30 endangered species of plants and animals make the Bay Area their home, including this Salt Marsh Harvest Mouse. Water Diversion: California's population will double in the next few decades, putting even greater pressure on salmon and other Bay wildlife that depend on fresh water flowing. Pollution: Each year, 88 million pounds of pesticides and toxic chemicals drain into the Bay from roads, lawns, farms, construction sites and abandoned mines. This pollution kills fish and birds, and endangers people who eat fish from the Bay. Landfill and Shoreline Development: Massive Bay-fill has been proposed for runways at San Francisco and Oakland International Airports. Lagoon housing developments threaten sensitive Bay shoreline in Marin County. Because these habitats persist in the midst of 7 million people, the Bay is still home to: 255 bird species 120 fish species 81 mammal species 30 reptile species 14 amphibian species Many of these creatures rely on wetland habitats and open waters of the ecosystem for spawning, nursing, and feeding. Nearly half of the birds on the Pacific Flyway and two-thirds of California's salmon pass through the Bay. Photo by Bob Walker ...
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