Record-high specific conductance and water temperature in San Francisco Bay during water year 2015

Open-File Report 2017-1022
By: , and 



The San Francisco estuary is commonly defined to include San Francisco Bay (bay) and the adjacent Sacramento–San Joaquin River Delta (delta). The U.S. Geological Survey (USGS) has operated a high-frequency (15-minute sampling interval) water-quality monitoring network in San Francisco Bay since the late 1980s (Buchanan and others, 2014). This network includes 19 stations at which sustained measurements have been made in the bay; currently, 8 stations are in operation (fig. 1). All eight stations are equipped with specific conductance (which can be related to salinity) and water-temperature sensors. Water quality in the bay constantly changes as ocean tides force seawater in and out of the bay, and river inflows—the most significant coming from the delta—vary on time scales ranging from those associated with storms to multiyear droughts. This monitoring network was designed to observe and characterize some of these changes in the bay across space and over time. The data demonstrate a high degree of variability in both specific conductance and temperature at time scales from tidal to annual and also reveal longer-term changes that are likely to influence overall environmental health in the bay.

In water year (WY) 2015 (October 1, 2014, through September 30, 2015), as in the preceding water year (Downing-Kunz and others, 2015), the high-frequency measurements revealed record-high values of specific conductance and water temperature at several stations during a period of reduced freshwater inflow from the delta and other tributaries because of persistent, severe drought conditions in California. This report briefly summarizes observations for WY 2015 and compares them to previous years that had different levels of freshwater inflow.

Suggested Citation

Work, P.A., Downing-Kunz, M.A., and Livsey, D., 2017, Record-high specific conductance and water temperature in San Francisco Bay during water year 2015: U.S. Geological Survey Open-File Report 2017–1022, 4 p.,

ISSN: 2331-1258 (online)

Study Area

Table of Contents

  • Abstract
  • Instrumentation and Data Collection
  • Water Year 2015 Records
  • Annual Mean Values and Relation to Freshwater Inflow
  • References Cited

Additional publication details

Publication type Report
Publication Subtype USGS Numbered Series
Title Record-high specific conductance and water temperature in San Francisco Bay during water year 2015
Series title Open-File Report
Series number 2017-1022
DOI 10.3133/ofr20171022
Year Published 2017
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) California Water Science Center, San Francisco Bay-Delta
Description 4 p.
Country United States
State California
Other Geospatial Sacramento-San Joaquin River Delta, San Francisco Bay
Online Only (Y/N) Y
Google Analytic Metrics Metrics page
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