san franisco bay by: randall alcorn. golden gate bridge
TRANSCRIPT
SAN FRANISCO BAY
By: Randall Alcorn
Golden Gate Bridge
History of the Bridge
• Took over 4yrs to construct
• Costs $35 million dollars
• 1.7 miles long in length
• Opened May 28,1937
Alcatraz
History of Alcatraz “Rock”
• Converted to Federal prison in 1934
• Thought had the perfect area for a prison
• 34 people tried to escape
• Closed March 21, 1963
The Bay Area
About the Bay
• 55,572 acres• 16,000 sq. miles• 50mi. Long and 3-13mi.
wide• 40% fresh water drains
into bay• Extends from California’s
San Pablo Bay to South San Francisco Bay
• 4 areas of the bay the north, central, and south San Francisco Bay, and San Pablo Bay
About the bay (cont.)
• 400ft is deepest area
• Relatively shallow, channel on 50 ft exists
• One of the most important coastal wintering and migratory habitats for Pacific flyway waterfowl
SAN FRANCISCO BAY
The development
Development (cont.)
• The bay was formed 10,000 yrs ago during the last ice age.
• Sea levels rose and inland through the “golden gate”
• Levels were rising at 1” per year, along with rivers and creeks coming into the area
• Sedimentation occurred
San Pablo Bay
San Pablo Bay (cont.)
• Shallow tidal estuary• 10mi. Across and
covers app. 90 sq miles
• Mostly fresh water but contains salt marshes and also mudflats
• Sacramento and San Joaquin Rivers empty
San Francisco Bay Estuary
Estuary
• Nation’s second largest/most biologically significant estuary on the Pacific Coast
• Made up of San Francisco Bay (north, south, and central) and the San Pablo Bay
• Interconnecting wetlands (sloughs, marshes, channels, rivers)
• Some areas are mixed salt/fresh water
Habitats
• Tidal Flats- Areas that are flooded during high tide and lose most the water during low tide
• Tidal Marsh- Areas flooded by high tide but retain some water during low tide.
• Seasonal Wetlands- Moist grassland and vernal pools.• Riparian Habitat- Boards creek, rivers, lakes• Non-tidal diked wetlands- Tidal marshes that are
isolated from tidal influence and maintain wetland features.
• Salt ponds- Large man-made ponds that are flooded with Bay water.
Tidal Marshes
• 190,000 acres now only 16,000
• The “kidneys” of Bays, purifying pollutants
• Produce large amounts of plant material
Tidal Marshes (cont.)
• Important for fish and waterfowl
• Vegetation consists of algae, sea lettuce, and eel grass
• High tide fish use the area for forage
• Low tide fish eating birds consume fish, that didn’t make it out
Tidal Marshes in 1900
Tidal Marshes 1990
Salt Ponds
• San Francisco Bay offers good area for salt production (Cargill Salt Company)
• Water is brought in from the bay into man-made ponds
• Provides food and habitat for more than 70 species of waterfowl and shorebirds
• San Francisco Bay Wildlife Refuge bought 16,500 acres of salt ponds (one of largest restoration attempts in America)
Salt Pond (cont.)
• 300 million dollars
• Take five years to fully restore but hope to:– Increase bays tidal wetland by 50%– Preserve open space– Improve water quality– Act as natural flood control – Prevent shoreline erosion – Provide habitat for endangered species
Importance of Wetlands in Bay
• San Francisco is heavily polluted, wetlands help filter pollutants.
• Soak up excess water, that could flood the bay
• Provides home for endangered species
• 70% of commercial fishing
Wetlands destroyed
• (Human influence) They are cheap, provide go location for business and are easy to build on.
• Exotic species brought in from ships
• They push out native species of plants and animals.
• 100 exotic species
Programs to help restore wetland habitats
• Ducks Unlimited
• San Pablo Bay National Wildlife Refuge
• San Francisco Bay Joint Venture
Programs (cont.)
• Ducks Unlimited• 20,000 acres of habitat• Help to directly benefit
endangered species and sensitive species
• Habitat improvement for waterfowl: lesser scaup, canvasback, northern pintail, and redhead.
• San Pablo Bay NWR• Open bay, tidal marshes,
mudflats, and seasonal and managed wetlands
• Marches have been greatly impacted; agriculture, draining, industrial use and water diversions
• 85% wetlands been altered.
• Refuge provides area for migratory waterfowl species.