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What's New for 1999

The History and Effects of Exotic Species in San Francisco Bay

Learn about:

  • what an exotic species is,
  • how they got to San Francisco Bay in the first place,
  • what damage they've done,
  • what they're doing now, and
  • what the future holds...

10 Meter DEMs of the Bay Area

We've added high-resolution 10 meter DEMs of the Bay Area to our USGS SF Bay Area digital map Web Site, BARD (Bay Area Regional Database).

The DEMs are in standard USGS format at a scale of 1:24,000.

Coverage is from Napa to Monterey.

Landsat 7 Image of the San Francisco Bay

Also check out the USGS Landsat 7 Home Page. Landsat 7 is an earth remote sensing satellite.

USGS Booth at the 1999 FOR Rivers Festivale

Rex and Laura take USGS Web sites on the road again!

The Access USGS--San Francisco Bay and Delta Web site was one of the featured Web sites at the USGS booth at the Friends of the River (FOR) Rivers Festival: San Francisco, February 20+21, 1999.

Indirect Measurement of Delta Outflow Using Ultrasonic Velocity Meters and Comparison with Mass-Balance Calculated Outflow

An article from the "Interagency Ecological Program (IEP) for the Sacramento-San Joaquin Estuary" Newsletter (Vol.11, No.1 --Winter 1998)

  • A measurement of the quantity of water flowing from the Sacramento-San Joaquin Delta into Suisun Bay (Delta outflow) has been desired by those studying and managing the San Francisco Bay/Delta estuary since the 1920's.
  • Historically, Delta outflow has been estimated using a mass-balance calculation that uses measured Delta inflows and exports, and imprecise estimates of consumptive use for the approximately 1,800 small agricultural diversions within the Delta.
  • Although the mass-balance method has worked reasonably well over the years, it has several shortcomings.
  • The USGS can now provide indirect measurements of Delta outflow by combining flow measurements from 4 of the 10 continuous flow monitoring stations currently operated by the USGS in the Delta.

Summary of Findings About Circulation and the Estuarine Turbidity Maximum in Suisun Bay, California

  • During the 1960s and 1970s, data collected in Suisun Bay were analyzed to develop a conceptual model of how water, salt, and sediment move within and through the Bay.
  • This conceptual model has been used to manage freshwater flows from the Sacramento-San Joaquin Delta to Suisun Bay to improve habitat for several threatened and endangered fish species.
  • Instrumentation used to measure water velocity, salinity, and suspended-solids concentration (SSC) greatly improved during the 1980s and 1990s.

The U.S. Geological Survey (USGS) has utilized these new instruments to collect one of the largest, high-quality hydrodynamic and sediment data sets available for any estuary. Analysis of these new data has led to the revision of the conceptual model of circulation and sediment transport in Suisun Bay.


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