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San Francisco Bay Delta

SF Bay Projects

San Francisco Bay Salinity Stations

Contact: David Schoellhamer, Research Hydrologist, dschoell@usgs.gov

Locations of water quality sondes in San Francisco Bay.

Locations of water quality sondes in San Francisco Bay.

Temperature and salinity are two key estuarine habitat variables. Understanding how these variables are distributed around the bay leads to a better understanding of habitat types and distribution in the Bay. Additionally, understanding the distribution of salinity in the Bay allows us to better understand the transport processes that drive material transport and supply throughout the Bay. Time series of water temperature and specific conductance (salinity is calculated from conductivity and water temperature) are needed (1) to improve our understanding of the hydrodynamics of the estuary (e.g., gravitational circulation), (2) for calibration of multi-dimensional flow and transport models of the Bay, (3) to better understand the distribution of physio-chemical habitat types throughout the Bay , and (4) to provide supporting data for numerous estuarine studies of the Bay and Delta.

The objective of this work is to measure the spatial and temporal variability of salinity and temperature in San Francisco Bay. The USGS will collect specific conductance (salinity) and temperature data on a 15-minute interval at the following six continuous monitoring stations in SFB:

The stations are currently installed, and regular maintenance includes approximately monthly visits to the sites for sensor calibration and cleaning, along with other routine maintenance of the water quality sondes and stations. All stations except Alcatraz and Dumbarton include instruments located at two depths, typically one each in the lower and upper half of the water column. The Alcatraz and Dumbarton stations have a single instrument located roughly at mid-depth. This project does not include data analysis.

This project addresses ecosystem and climate strategic directions in the USGS science plan. Understanding how these variables are distributed around the bay leads to a better understanding of habitat types and distribution in the Bay. Understanding how these variables vary in time leads to a better understanding of the effects of freshwater flow and climate.

Relevant work:

Shellenbarger, G.G. and Schoellhamer, D.H., 2011, Continuous salinity and temperature data from San Francisco Bay, California, 1982-2002: trends and the salinity-freshwater inflow relationship: Journal of Coastal Research, v. 27, no. 6, p. 1191-1201.

U.S. Geological Survey, 2007, Facing tomorrow’s challenges—U.S. Geological Survey science in the decade 2007–2017: U.S. Geological Survey Circular 1309, 70 p.

Wagner, R.J., Boulger, R.W., Jr., Oblinger, C.J., and Smith, B.A., 2006, Guidelines and standard procedures for continu¬ous water-quality monitors—Station operation, record computation, and data reporting: U.S. Geological Survey Tech¬niques and Methods 1–D3, 51 p.

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