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)

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 July 2017. The dataset includes up to 706 observations (including field replicates) per sediment parameter, reflecting 93 unique sampling locations, with each location having been sampled from 1 to 28 times (excluding field replicates) over this 8-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 (20–28 times, primarily during 2015–2017) 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). This data release includes six data tables given both as excel (*.xlxs) and machine readable format (*.csv): 1) ‘CCSB.SED_data.dictionary’, the Data Dictionary, which provides definitions and details related to the other five data tables and includes citations of analytical methods; 2) ‘CCSB.SED_2010-17’, the primary dataset with spatial/temporal sediment and pore water analyses; 3) ‘CCSB.SED_seq’, a sub-set of sediment samples (33 sites collected during May 2013) assayed for Hg using a 5-fraction sequential extraction procedure; 4) ‘CCSB.SED_grain.size’, data on detailed sediment grain-size distribution (by laser-scattering Coulter counter) for 615 unique samples (plus n=65 field duplicates); 5) ‘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 (at 15 of the 33 sites); and 6) ‘CCSB.SED¬_QA’, quality assurance data summary. The mapping of the physical site locations can be found on the companion child page associated with this product (‘see associated items’).

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)

The Cache Creek Settling Basin (CCSB) is a 13.3 km2 leveed basin located at the terminal drainage of the Cache Creek watershed, immediately NE of the town of Woodland (Yolo County), California and approximately 18 km NW of Sacramento, California. The basin was constructed by the U.S. Army Corps of Engineers (completed in 1937 and modified in 1993) for the purpose of trapping suspended sediment transported from the upper Cache Creek watershed during high-flow events, thus preventing sediment from entering the Yolo Bypass, a larger downstream floodwater conveyance and agricultural zone. In addition to trapping suspended sediment, the CCSB also traps sediment-associated mercury (Hg), which is particularly elevated in the upper watershed, owing to natural Hg deposits and associated historic Hg mining areas. The CCSB is a multi-use area containing a number of habitat types that are typical of the California Central Valley region, including: open-water (stream, canal), riparian, floodplain (woody, non-woody), and agriculture (row crop fields) habitats. This dataset includes shallow surface sediment (top 0–2 cm interval) constituent concentration data (primarily) and microbial methylmercury production potential rate data (limited) collected between April 2010 and July 2017 from the above-noted habitats to assess spatial and temporal variations in sediment geochemistry and mercury speciation within the CCSB. The dataset is presented in two sections (child pages): one has the constituent concentration and microbial rate data, and the other includes results of habitat mapping that was conducted within the CCSB for the purpose of data analysis.

The Cache Creek Settling Basin (CCSB) is a 13.3 km2 leveed basin located at the terminal drainage of the Cache Creek watershed, immediately NE of the town of Woodland (Yolo County), California and approximately 18 km NW of Sacramento, California. The basin was constructed by the U.S. Army Corps of Engineers (completed in 1937 and modified in 1993) for the purpose of trapping suspended sediment transported from the upper Cache Creek watershed during high-flow events, thus preventing sediment from entering the Yolo Bypass, a larger downstream floodwater conveyance and agricultural zone. In addition to trapping suspended sediment, the CCSB also traps sediment-associated mercury (Hg), which is particularly elevated in the upper watershed, owing to natural Hg deposits and associated historic Hg mining areas. The CCSB is a multi-use area containing a number of habitat types that are typical of the California Central Valley region, including: open-water (stream, canal), riparian, floodplain (woody, non-woody), and agriculture (row crop fields) habitats. This dataset includes shallow surface sediment (top 0–2 cm interval) constituent concentration data (primarily) and microbial methylmercury production potential rate data (limited) collected between April 2010 and July 2017 from the above-noted habitats to assess spatial and temporal variations in sediment geochemistry and mercury speciation within the CCSB. The dataset is presented in two sections (child pages): one has the constituent concentration and microbial rate data, and the other includes results of habitat mapping that was conducted within the CCSB for the purpose of data analysis.

The Cache Creek Settling Basin (CCSB) is a 13.3 km2 leveed basin located at the terminal drainage of the Cache Creek watershed, immediately NE of the town of Woodland (Yolo County), California and approximately 18 km NW of Sacramento, California. The basin was constructed by the U.S. Army Corps of Engineers (completed in 1937 and modified in 1993) for the purpose of trapping suspended sediment transported from the upper Cache Creek watershed during high-flow events, thus preventing sediment from entering the Yolo Bypass, a larger downstream floodwater conveyance and agricultural zone. In addition to trapping suspended sediment, the CCSB also traps sediment-associated mercury (Hg), which is particularly elevated in the upper watershed, owing to natural Hg deposits and associated historic Hg mining areas. The CCSB is a multi-use area containing a number of habitat types that are typical of the California Central Valley region, including: open-water (stream, canal), riparian, floodplain (woody, non-woody), and agriculture (row crop fields) habitats. This dataset includes shallow surface sediment (top 0–2 cm interval) constituent concentration data (primarily) and microbial methylmercury production potential rate data (limited) collected between April 2010 and July 2019 from the above-noted habitats to assess spatial and temporal variations in sediment geochemistry and mercury speciation within the CCSB. The dataset is presented in two sections (child pages): one has the constituent concentration and microbial rate data, and the other includes results of habitat mapping that was conducted within the CCSB for the purpose of data analysis. First posted – October 16, 2018 (available from author) Revised – July, 2021 (version 2.0)

The Cache Creek Settling Basin (CCSB) is a 13.3 km2 leveed basin located at the terminal drainage of the Cache Creek watershed, immediately NE of the town of Woodland (Yolo County), California and approximately 18 km NW of Sacramento, California. The basin was constructed by the U.S. Army Corps of Engineers (completed in 1937 and modified in 1993) for the purpose of trapping suspended sediment transported from the upper Cache Creek watershed during high-flow events, thus preventing sediment from entering the Yolo Bypass, a larger downstream floodwater conveyance and agricultural zone. In addition to trapping suspended sediment, the CCSB also traps sediment-associated mercury (Hg), which is particularly elevated in the upper watershed, owing to natural Hg deposits and associated historic Hg mining areas. The CCSB is a multi-use area containing a number of habitat types that are typical of the California Central Valley region, including: open-water (stream, canal), riparian, floodplain (woody, non-woody), and agriculture (row crop fields) habitats. This dataset includes shallow surface sediment (top 0–2 cm interval) constituent concentration data (primarily) and microbial methylmercury production potential rate data (limited) collected between April 2010 and July 2017 from the above-noted habitats to assess spatial and temporal variations in sediment geochemistry and mercury speciation within the CCSB. The dataset is presented in two sections (child pages): one has the constituent concentration and microbial rate data, and the other includes results of habitat mapping that was conducted within the CCSB for the purpose of data analysis.

The Cache Creek Settling Basin (CCSB) is a 13.3 km2 leveed basin located at the terminal drainage of the Cache Creek watershed, immediately NE of the town of Woodland (Yolo County), California and approximately 18 km NW of Sacramento, California. The basin was constructed by the U.S. Army Corps of Engineers (completed in 1937 and modified in 1993) for the purpose of trapping suspended sediment transported from the upper Cache Creek watershed during high-flow events, thus preventing sediment from entering the Yolo Bypass, a larger downstream floodwater conveyance and agricultural zone. In addition to trapping suspended sediment, the CCSB also traps sediment-associated mercury (Hg), which is particularly elevated in the upper watershed, owing to natural Hg deposits and associated historic Hg mining areas. The CCSB is a multi-use area containing a number of habitat types that are typical of the California Central Valley region, including: open-water (stream, canal), riparian, floodplain (woody, non-woody), and agriculture (row crop fields) habitats. This dataset includes shallow surface sediment (top 0–2 cm interval) constituent concentration data (primarily) and microbial methylmercury production potential rate data (limited) collected between April 2010 and July 2019 from the above-noted habitats to assess spatial and temporal variations in sediment geochemistry and mercury speciation within the CCSB. The dataset is presented in two sections (child pages): one has the constituent concentration and microbial rate data, and the other includes results of habitat mapping that was conducted within the CCSB for the purpose of data analysis. First posted – October 16, 2018 (available from author) Revised – July, 2021 (version 2.0)

The geospatial data presented here as ArcGIS layers denote landcover/landuse classifications to support field sampling efforts that occurred within the Cache Creek Settling Basin (CCSB) from 2010-2017. Manual photointerpretation of a National Agriculture Imagery Program (NAIP) dataset collected in 2012 was used to characterize landcover/landuse categories (hereafter habitat classes). Initially 9 categories were assigned based on vegetation structure (Vegtype1). These were then parsed into two levels of habitat classes that were chosen for their representativeness and use for statistical analyses of field sampling. At the coarsest level (Landcover 1), five habitat classes were assigned: Agriculture, Riparian, Floodplain, Open Water, and Road. At the more refined level (Landcover 2), ten habitat classes were nested within these five categories. Agriculture was not further refined within Landcover 2, as little consistency was expected between years as fields rotated between corn, pumpkin, tomatoes, and other row crops. Riparian habitat, marked by large canopy trees (such as Populus fremontii (cottonwood)) neighboring stream channels, also was not further refined. Floodplain habitat was separated into two categories: Mixed NonWoody (which included both Mowed and Barren habitats) and Mixed Woody. This separation of the floodplain habitat class (Landcover1) into Woody and NonWoody was performed with a 100 m2 moving window analysis in ArcGIS, where habitats were designated as either ≥50% shrub or tree cover (Woody) or <50%, and thus dominated by herbaceous vegetation cover (NonWoody). Open Water habitat was refined to consider both agricultural Canal (created) and Stream (natural) habitats. Road habitat was refined to separate Levee Roads (which included both the drivable portion and the apron on either side) and Interior roads, which were less managed. The map was tested for errors of omission and commission on the initial 9 categories during November 2014. Random points (n=100) were predetermined, and a total of 80 were selected for field verification. Type 1 (false positive) and Type 2 (false negative) errors were assessed. The survey indicated several corrections necessary in the final version of the map. 1) We noted the presence of woody species in “NonWoody” habitats, especially Baccharus salicilifolia (mulefat). Habitats were thus classified as “Woody” only with ≥50% presence of canopy species (e.g. tamarisk, black willow) 2) Riparian sites were over-characterized, and thus constrained back to “near stream channels only”. Walnut (Juglans spp) and willow stands alongside fields and irrigation canals were changed to Mixed Woody Floodplain. Fine tuning the final habitat distributions was thus based on field reconnaissance, scalar needs for classifying field data (sediment, water, bird, and fish collections), and validation of data categories using species observations from scientist field notes. Calibration was made using point data from the random survey and scientist field notes, to remove all sources of error and reach accuracy of 100%. The coverage “CCSB_Habitat_2012” is provided as an ARCGIS shapefile based on a suite of 7 interconnected ARCGIS files coded with the suffixes: cpg, dbf, sbn, sbx, shp, shx, and prj. Each file provides a component of the coverage (such as database or projection) and all files are necessary to open the “CCSB_Habitat_2012.shp” file with full functionality.

The geospatial data presented here as ArcGIS layers denote landcover/landuse classifications to support field sampling efforts that occurred within the Cache Creek Settling Basin (CCSB) from 2010-2017. Manual photointerpretation of a National Agriculture Imagery Program (NAIP) dataset collected in 2012 was used to characterize landcover/landuse categories (hereafter habitat classes). Initially 9 categories were assigned based on vegetation structure (Vegtype1). These were then parsed into two levels of habitat classes that were chosen for their representativeness and use for statistical analyses of field sampling. At the coarsest level (Landcover 1), five habitat classes were assigned: Agriculture, Riparian, Floodplain, Open Water, and Road. At the more refined level (Landcover 2), ten habitat classes were nested within these five categories. Agriculture was not further refined within Landcover 2, as little consistency was expected between years as fields rotated between corn, pumpkin, tomatoes, and other row crops. Riparian habitat, marked by large canopy trees (such as Populus fremontii (cottonwood)) neighboring stream channels, also was not further refined. Floodplain habitat was separated into two categories: Mixed NonWoody (which included both Mowed and Barren habitats) and Mixed Woody. This separation of the floodplain habitat class (Landcover1) into Woody and NonWoody was performed with a 100 m2 moving window analysis in ArcGIS, where habitats were designated as either ≥50% shrub or tree cover (Woody) or <50%, and thus dominated by herbaceous vegetation cover (NonWoody). Open Water habitat was refined to consider both agricultural Canal (created) and Stream (natural) habitats. Road habitat was refined to separate Levee Roads (which included both the drivable portion and the apron on either side) and Interior roads, which were less managed. The map was tested for errors of omission and commission on the initial 9 categories during November 2014. Random points (n=100) were predetermined, and a total of 80 were selected for field verification. Type 1 (false positive) and Type 2 (false negative) errors were assessed. The survey indicated several corrections necessary in the final version of the map. 1) We noted the presence of woody species in “NonWoody” habitats, especially Baccharus salicilifolia (mulefat). Habitats were thus classified as “Woody” only with ≥50% presence of canopy species (e.g. tamarisk, black willow) 2) Riparian sites were over-characterized, and thus constrained back to “near stream channels only”. Walnut (Juglans spp) and willow stands alongside fields and irrigation canals were changed to Mixed Woody Floodplain. Fine tuning the final habitat distributions was thus based on field reconnaissance, scalar needs for classifying field data (sediment, water, bird, and fish collections), and validation of data categories using species observations from scientist field notes. Calibration was made using point data from the random survey and scientist field notes, to remove all sources of error and reach accuracy of 100%. The coverage “CCSB_Habitat_2012” is provided as an ARCGIS shapefile based on a suite of 7 interconnected ARCGIS files coded with the suffixes: cpg, dbf, sbn, sbx, shp, shx, and prj. Each file provides a component of the coverage (such as database or projection) and all files are necessary to open the “CCSB_Habitat_2012.shp” file with full functionality.