Water-quality data in the Cache Creek watershed and settling basin, Yolo County, California

This dataset includes water-quality and suspended-sediment data for 109 environmental samples collected at 14 surface-water sites in the Cache Creek (Cache C) watershed, Yolo County, California, between December 2019 and March 2024, and data for 18 associated quality-control samples (replicates and blanks). Around three-quarters of the samples were collected from three sites: Cache C Outflow From Settling Basin Near Woodland CA (USGS-11452900), Cache C at Yolo CA (USGS-11452500), and Cache C at Rumsey CA (USGS-11451800). The remaining samples were collected at sites along the Cache C overflow weir or in the settling basin itself. Constituents analyzed include total mercury and methylmercury in dissolved and particulate forms, reactive divalent mercury in particulate form, suspended sediment, dissolved organic carbon, and absorption-fluorescence data for dissolved organic matter. Dissolved forms of mercury and dissolved organic carbon were determined on water that passed through a 0.3 micron (um) filter membrane. The grain-size distribution of suspended sediment in selected samples is also reported. All tables are provided as machine readable Comma Separated Values File (.csv) files. This data release contains data for the same constituents for samples collected at the same sites in 2009-2019 as detailed in Alpers and other (2025).