San Francisco Bay Delta

Continuous Monitoring of Water Quality and Suspended-Sediment Transport in the San Francisco Bay and Delta

Our group at the USGS continuously monitors suspended-sediment concentration (SSC), turbidity, dissolved oxygen, temperature, salinity, and water level at many sites throughout the San Francisco Bay (Bay) and the Sacramento-San Joaquin Rivers Delta (Delta).

Our work began in 1988 to explore the spatial and temporal variability of water quality and sediment transport and to provide decision makers, resource managers, and the public with the most up-to-date knowledge. Topics we study include water quality, sediment transport, water clarity, erosion and deposition, sediment-associated contaminants and habitat quality, wetland restoration, and sea level rise.


Within the Bay, fresh water from California rivers mixes with salt water from the Pacific Ocean. This mixing is affected in part by tides, waves, and fresh water inflow and itself affects water quality, sediment transport, and ecology in the Bay and Delta. Sediment transport is a dynamic process that affects sediment deposition and erosion, concentrations of toxic substances that adsorb to sediment, quantity and quality of habitat for fish and benthic organisms, and amount of light available for photosynthesis.

Our continuous monitoring of the Bay and Delta provides high quality data to improve our knowledge of processes affecting water quality in this complex and important system.

Purpose and Scope

The purpose of this web page is to provide access to and background information on our continuous monitoring data for salinity, temperature, water level, dissolved oxygen, turbidity, and SSC in the Bay and Delta. Our data are collected every 15 minutes at multiple sites throughout the Bay and Delta (see map) and at one or two water depths. Collection of salinity, temperature, and water level time series began in 1988; collection of turbidity and SSC time series began in 1991; and collection of dissolved oxygen time series began in 2012. All data undergo a rigorous review process that includes editing, quality assurance, and approval. The results are high quality data available for use by scientists, resource managers, educators, and the general public. Our data can be accessed for visualization and/or retrieval via the USGS National Water Information System (NWIS). Our most recent fact sheet highlights our data collected between 2011 and 2013 and is available online.

Map of our present and historical continuous monitoring stations in the Bay (blue markers) and Delta (green markers). Zoom in and click on markers to access data.

SF Bay Projects

California Water Conditions

Real-Time California Streamflow Conditions