| What's New for 1997 |
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| To preserve a viable wetland habitat around the Bay, management agencies have begun to identify the threats to existing wetlands and to determine viable strategies for wetland restoration in areas that are now diked agricultural land or salt evaporating ponds. Those agencies, in coordination with other appropriate groups, have initiated the first major wetland restoration endeavor to use dredge spoils, the Sonoma Baylands Restoration Project. USGS is studying how the structure and form of the wetland changes over time to aid agencies in evaluating this important experiment. |
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The spring runoff from the Sierra Nevada is the last gasp of plentiful freshwater inflow to San Francisco Bay and Delta before the summertime dry period. The pulse is evidently a response to almost simultaneous changes in temperatures over much of the western United States. A low pressure (winter) pattern is replaced (within days) by a strong and expanding high-pressure pattern, accompanied by high air temperature and a persistent surge in snowmelt-driven discharge. Knowing when the runoff surge will occur is important for reservoir, resource, and flood managers. USGS scientists believe it may be possible to predict this surge as much as a week in advance. Three papers written for the Interagency Ecological Program chart the progress of this important approach.
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Climate is the BIG SIGNAL in stream and river discharge records. This signal runs through the watershed and is ultimately carried into the ocean. Using new methods and the USGS historical water flow for the Merced River as it passes through Yosemite National Park, it now appears to be possible to identify and at least partially separate human from natural climate effects on discharge and to determine the Bay's salinity response on DAILY to DECADAL time scales. See how USGS scientists are putting together the pieces of a puzzle linking climate, river basins, and the estuary.
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| Sedimentation in San Pablo Bay changed dramatically during the past 140 years. From 1856 (the earliest detailed hydrographic survey) until at least the late 1800's hydraulic mining debris filled San Pablo Bay. During the early 1900's sedimentation slowed and, in the late 1900's, San Pablo Bay was erosional as the supply of hydraulic mining debris decreased and Central Valley water projects diminished sediment supply to the Delta and Bay. These pages show change in sedimentation using computer analysis and display of historical hydrographic surveys made by the US Coast and Geodetic Survey (USCGS) and the National Ocean Survey (NOS). |
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Sediment is a continuing concern to navigation in San Francisco Bay. Dredging is expensive, and dredge spoils may be environmentally hazardous. USGS is helping managers who must decide on whether, where, and how to dredge, understand basic patterns and processes of sediment transport. High resolution multibeam backscatter and bathymetry images were collected near Alcatraz and Tiburon and then processed to create a variety of maps that help delineate the morpology and composition of the bay floor. Some of these products were merged with Landsat data, giving a unique peek above and beneath the surface of San Francisco Bay.
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For almost three decades USGS has maintained a program of research and observation in San Francisco Bay. The program includes regular measurements of water quality along a 145 kilometer transect spanning the length of the entire estuarine system, from the South Bay to the Sacramento River. This website describes the measurement program and displays results of water quality measurements (chlorophyll, salinity, temperature, and light penetration). Users can choose to see these variables plotted for recent cruises, see patterns of water quality change for 1993-1995 and for selected locations since 1977, and obtain tables of measurements. The site comes complete with full explanations of the measuring devices, summary of the program, glossary, bibliography, and many examples.
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Primary Production is the synthesis of new plant matter by microscopic plants (algae) through the process of photosynthesis. Learn how USGS scientists measure algae in the Bay and how its total mass can be compared to that of Humphrey, the humpback whale.
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| Highlight Archives |
| 2005 - 2004 - 2002-03 - 2001 - 2000 - 1999 - 1998 - 1997 - 1995-96 |
U.S. Department of the Interior |
U.S. Geological Survey
