San Francisco Bay High-frequency Water Quality Sensor Data

The Moored Sensor Program (MSP) is a network of high-frequency continuous water quality sensors distributed throughout San Francisco Bay. The network was first established in 2013 as part of the Nutrient Management Strategy, a program tasked with building the scientific foundation needed to inform nutrient-related management decisions in the Bay. The MSP has grown from two monitoring sites to more than fourteen, with more anticipated. Data from the sensors track changes in water quality conditions over time, and enable mechanistic interpretations, calibration, and refinement of a state-of-the-art hydrodynamic/biogeochemical model. The primary instrument the MSP uses is the YSI EXO2 multiparameter sonde, which records data at a 15 minute interval. Measured parameters vary by station location and include temperature, conductivity (salinity), depth, dissolved oxygen, chlorophyll a, blue-green algae, turbidity, fluorescent dissolved organic matter, and pH. EXO2s are serviced every 3–6 weeks. This consists of data download, sensor cleaning, and battery replacement. The instruments are retrieved from the field every 2–4 months for laboratory calibration following procedures outlined in the instrument manual. During this time they are field-swapped with new sondes to prevent data gaps. Following download, data are subject to a semi-automated quality assurance/quality control procedure that includes manual inspection and data cleaning. The current dataset includes water quality data from 2013-2021 collected at 11 stations [SLM, SHL, HAY, SMB, DMB, NEW, MOW, COY, ALV, GUAD, POND]. More recent EXO2 data from an additional 3 stations [EMR, SPA8, SPA4] will be uploaded after passing through quality assurance/quality control procedures. The Nutrient Management Strategy collects and processes data in collaboration with USGS California Water Science Center, USGS Pacific Coastal and Marine Science Center, and the California Conservation Corps Watershed Stewards Program.