This report presents results from a three-year effort (2022-2024) to estimate continuous suspended sediment concentration (SSC) in the South Bay (SB) and Lower South Bay (LSB) regions of San Francisco Bay (SFB). We used discrete SSC samples to calibrate high-frequency (15-min) turbidity measurements from the Nutrient Management Strategy’s (NMS) moored sensor array, resulting in high-frequency SSC estimates at 8 study sites. This effort represents a collaboration between the NMS, San Francisco Bay Regional Monitoring Program, and South Bay Salt Pond Restoration Project.

The moored sensor array used for turbidity data collection consisted of 7 YSI EXO2 multiparameter sondes and 1 PME C7 turbidity-only sensor. We evaluated several turbidity – SSC models for data from the 7 EXO2 sites, ultimately selecting a series of 3 slope-only (y-intercept = 0) least squares linear regressions (LSLRs) from log10-log10 transformed data grouped together based on 3 habitats types in SB and LSB (channel, slough, and shoal). This calibration model represents a change from Year 1 and Year 2 reports, which utilized a linear mixed effect model (LMM). Turbidity from the C7 site was also calibrated using a slope-only LSLR from log10-log10 data. Calibrations at all sites showed reasonable agreement between log10(turb) and log10(SSC), with R2 = 0.89, 0.87, and 0.85 for regressions at the channel, slough, and shoal sites, respectively, and R2 = 0.93 for the C7 site. From these calibrations we created continuous 15-min SSC datasets at 8 locations, representing 1 channel, 4 shoal, and 3 slough sites. These high-frequency SSC data are designed for use in more targeted studies of SFB SSC dynamics, and will be made available for download from the San Francisco Estuary Institute (SFEI) website.