This dataset includes shallow surface sediment (top 0–2 cm interval) constituent concentration data (primarily) and microbial methylmercury production potential rate data (limited) collected from the Cache Creek Settling Basin (CCSB), Yolo County, California, between April 2010 and November 2019. The dataset includes up to 723 observations (including field replicates) per sediment parameter, reflecting 93 unique sampling locations, with each location having been sampled from 1 to 29 times (excluding field replicates) over this 10-year period. There were four spatially intensive field campaigns conducted (February–March 2013, May 2013, October–November 2014, and January–March 2015), during which at least 90 sites were sampled. A sub-set of 13 sites were sampled intensively (20–29 times, primarily during 2015–2017, and 2019) to create a more detailed monthly time-series at these locations. Sampling was conducted over a range of hydrologic conditions, from periods when the basin was essentially dry (no overlying water, even in ‘open-water’ habitats) to periods when the basin was nearly fully flooded (most sites with overlying water). Analyses in this dataset include: bulk sediment: total mercury, methyl mercury, reactive mercury(ll), iron speciation, total reduced sulfur, loss on ignition, dry weight, bulk density, porosity, grain-size (sieved), grain size distribution; pore water: total mercury, methyl mercury, dissolved organic carbon, sulfate, chloride, sulfide, and isotopic delta 34-S of sulfate. This data release is a revision, which includes six data tables given both as excel (.xlsx) and machine readable (comma-separated values, .csv) format: 1) ‘T1_CCSB_SED_data_dictionary _ver2.0’, the Data Dictionary, which provides definitions and details related to the other five data tables and includes citations of analytical methods; 2) ‘T2_CCSB_SED_ver2.0’, the primary dataset with spatial/temporal sediment and pore water analyses; 3) ‘T3_CCSB_SED_seq_extr’, a sub-set of sediment samples (33 sites collected during May 2013) assayed for Hg using a 5-fraction sequential extraction procedure; 4) ‘T4_CCSB_SED_grain_size_ver2.0’, data on detailed sediment grain-size distribution (by laser-scattering) for 630 unique samples (plus n=67 field duplicates); 5) ‘T5_CCSB_SED_size_frac’, a sub-set of sediment samples (33 sites collected during May 2013) size-fractioned into 5 size classes and assayed for total mercury and limited suite of parameters, including particulate surface area (15 of the 33 sites); and 6) ‘T6_CCSB_SED_QA_ver2.0’, quality assurance data summary. The mapping of the physical site locations can be found on the companion child page associated with this product (https://www.sciencebase.gov/catalog/item/607625f2d34e018b3201cc1b) First posted – October 16, 2018 (available from author) Revised – July, 2021 (version 2.0)