Charles N. Alpers Shanna L. Miller Jennifer L. Agee Mark C. Marvin-DiPasquale Le H. Kieu Evangelos Kakouros Angela M. Hansen Jacob A. Fleck Alfred J. Ward Patrick T. Watanabe George L. Bennett V 20250411 spreadsheet https://www.sciencebase.gov/ U.S. Geological Survey data release https://doi.org/10.5066/F70R9N9H This dataset includes water-quality and sediment data for 647 environmental samples collected at 53 surface-water sites in Cache Creek (Cache C) watershed, Yolo County, California, between December 2009 and April 2019, and data for 190 associated quality-control samples (replicates and blanks). About 90 percent of the samples were collected at the following six primary sites that were sampled most frequently, and the other 39 extra sites were sampled only 1-5 times each. In addition, continuous turbidity measurements were made at 8 sites to aid with the calibration of turbidity measurements. The sites Cache C at Rumsey (11451800), Cache C at Yolo (11452500), and CCSB Inlet at Rd 102 (11452600) are upstream of the Cache C Settling Basin (CCSB); all other sites are in the CCSB and are shown on the map included in this data release. NWIS_Site_Number: Field_ID: 11451800 Cache C at Rumsey 11452500 Cache C at Yolo 11452600 CCSB Inlet at Rd.102 11452900 CCSB Outlet 11452800 CCSB S. Abutment Spillway 384115121402501 CCSB N. Abutment Spillway 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. The grain-size distribution of suspended sediment in selected samples is also reported. Six data tables and a Data Dictionary were prepared for this data release. All tables are provided as machine readable tab-delimited text (*.txt) files and as Excel formatted (*.xlsx) files. The data dictionary provides definitions and details presented in the data tables, including analytical methods citations. Two of the six data tables present and summarize quality control results collected for the study. The Cache Creek Settling Basin (CCSB) is a 13.3 kilometer squared (km2) leveed basin located at the terminal drainage of the Cache Creek watershed, immediately northeast of the town of Woodland, California and approximately 18 km northwest of Sacramento, California. The settling 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 watershed during high-flow events by Cache Creek, thus preventing sediment from entering the Yolo Bypass, a larger 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. As part of its Total Maximum Daily Load program, the California Central Valley Regional Water Quality Control Board has a goal to reduce the amount of Hg entering the Sacramento – San Joaquin Delta by increasing the trap efficiency of the CCSB from approximately 50% (previously estimated for the period 1984–2003) to 75% (Wood and others, 2010). The study associated with this data product has two primary goals: a) to obtain estimates of the trap efficiency of the CCSB during 2010–2019 for both particulate and dissolved Hg species (total Hg and methylmercury); and b) to improve understanding of Hg biogeochemistry and bioaccumulation within the CCSB. This data product is focused on water-quality data related to trap efficiency (goal a); and data on the within-basin sediment component of this larger study (goal b). Results of trap efficiency calculations will be reported separately. 20091229 20190417 observed In work Irregular Polygon Includes USGS Site Number 11451800 CACHE C A RUMSEY CA in the Northwest Corner and USGS Site Number 11452900 CACHE C OUTFLOW FROM SETTLING BASIN NR WOODLAND CA in the Southeast Corner -122.2395 -121.6702 38.8914 38.6755 USGS Thesaurus mercury biochemistry mercury contamination field sampling geochemistry chemical analysis turbidity surface water (non-marine) water quality grain-size analysis None suspended sediment methylmercury dissolved organic matter excitation-emission matrix spectra USGS Metadata Identifier USGS:598a209fe4b09fa1cb0cccf5 Geographic Names Information System (GNIS) Yolo By-pass Cache Creek Settling Basin Sacramento River Watershed Woodland, California Yolo County Sacramento–San Joaquin River Delta Cache Creek Yolo, California Rumsey, California None. Please see 'Distribution Info' for details. None. Users are advised to read the dataset's metadata thoroughly to understand appropriate use and data limitations. It is requested that the suggested citation for this USGS data release be included in any publications that reference or utilize these data. Charles N Alpers U.S. Geological Survey, SOUTHWEST REGION Research Chemist mailing address

6000 J Street Placer Hall

Sacramento CA 95819 US 916-278-3134 916-278-3070 cnalpers@usgs.gov Funding from the California Department of Water Resources (DWR) and U.S. Geological Survey water cooperative matching funds. Microsoft Office 365 Excel Version 2402 (Build 17328.20452) Mark C. Marvin-DiPasquale Elizabeth B. Stumpner Charles N. Alpers Lisamarie Windham-Myers Jacob A. Fleck Le Kieu Evangelos Kakouros James L. Orlando Peter A. Bennett Shanna L. Miller 2021 dataset https://www.sciencebase.gov U.S. Geological Survey U.S. Geological Survey data release https://doi.org/10.5066/p9mdxr3m Michelle R. Arias Charles N. Alpers Mark C. Marvin-DiPasquale Christopher C. Fuller Jennifer L. Agee Michelle Sneed Andrew Y. Morita Antonia J. Salas 2017 publication Data Series Data Series 1061 Reston, VA US Geological Survey U.S. Geological Survey Data Series Report https://doi.org/10.3133/ds1061 Jennifer L. Agee Charles N. Alpers Mark C. Marvin-DiPasquale Michelle R. Arias Christopher C. Fuller Michael Hedgpeth Le H. Kieu Kevin D. Kinnard Shanna L. Miller Patrick T. Watanabe Shaun M. Baesman 20210915 tabular digital data https://www.sciencebase.gov U.S. Geological Survey U.S. Geological Survey data release https://doi.org/10.5066/P91NXACC Michael R. Hedgpeth Charles N. Alpers Patrick T. Watanabe Kate M. Campbell Tyler J. Kane David A. Roth 20230609 tabular digital data https://www.sciencebase.gov U.S. Geological Survey U.S. Geological Survey data release https://doi.org/10.5066/P9S4NNR2 Michelle L. Wood Patrick W. Morris Janis Cooke Stephen J. Louie 20100201 publication Rancho Cordova, CA Central Valley Regional Water Quality Control Board https://www.waterboards.ca.gov/rwqcb5/water_issues/tmdl/central_valley_projects/delta_hg/archived_delta_hg_info/april_2010_hg_tmdl_hearing/apr2010_bpa_staffrpt_final.pdf U.S. Geological Survey 20241203 application/service Reston, VA U.S. Geological Survey https://doi.org/10.5066/F7P55KJN U.S. Geological Survey 2018 publication Techniques and Methods Book 9, Chap. A0 Reston, VA U.S. Geological Survey Version 1.1 https://doi.org/10.3133/tm9A0 WQ-Review (v2.2), a toolbox for discrete water-quality data review and exploration of the data stored in the National Water Information System (NWIS), was used to evaluate a large portion of the dataset. Field and laboratory replicates were collected to allow for the evaluation of measurement accuracy and reproducibility. Field blanks were collected to assess equipment cleaning techniques and other potential sources of measurement bias. A summary of each of these QA/QC types is described in the process step section of this data release and summary statistics of the QA/QC samples is presented in table T6_QAQC. Data stored in NWIS were cross-checked and verified. Field data sheets were reviewed during the data compilation process for this data release. There are some differences between results stored in NWIS when compared to this ScienceBase Data Release. Results with values of 1.5 were rounded down in NWIS to a value of 1 while results with values of 1.5 were rounded up to 2 in this ScienceBase Data Release. Additionally, some results were censored because they had concentrations less than the MDL and marked as "nondetect" in this data release are still reported in NWIS with the value provided by the laboratory. Files were reviewed to make sure they were complete. Data set is considered complete for the information presented, as described in the abstract. Users are advised to read the rest of the metadata record carefully for additional details. No formal positional accuracy tests were conducted No formal positional accuracy tests were conducted U.S. Geological Survey 20241204 application/service https://doi.org/10.5066/F7P55KJN Digital and/or Hardcopy 20091229 20190417 See Supplemental Info U.S. Geological Survey, 2024 U.S. Geological Survey National Water Information System database that stores some of the water-quality data presented in the data release. Sampling: A total of 830 samples (environmental and quality control) were collected from 53 surface-water sites between December 2009 and April 2019. About 90 percent of the samples were collected from 6 of the sites. These 6 sites also were instrumented for continuous measurement of discharge and field water-quality parameters. These 6 sites were selected to provide data necessary for calculation of trapping efficiency of mercury within the Cache Creek Settling Basin (CCSB). NWIS_Site_Number Field_ID count min date max date 11451800 Cache C at Rumsey 104 12/11/2014 4/15/2019 11452500 Cache C at Yolo 46 2/11/2014 4/17/2019 11452600 CCSB Inlet at Rd.102 123 1/21/2010 4/26/2017 11452900 CCSB Outlet 95 1/21/2010 4/17/2019 11452800 CCSB S. Abutment Spillway 66 1/21/2010 4/17/2019 384115121402501 CCSB N. Abutment Spillway 47 12/3/2012 4/17/2019 About 10 percent of the samples were collected from 39 of the sites, most of which were sampled only one time. These sites were selected to investigate water-quality variability within the CCSB. A map (CCSB_MAP_USGS2024_CC0.jpg) was generated and included in this data release that shows the location of all but two of the sites. The two sites not shown on the map are the surface water sites upstream from the CCSB (Cache C at Rumsey and Cache C at Yolo). Turbidity samples were collected from 8 sites along the CCSB weir. At these locations water-quality instruments (sondes) capable of continuous turbidity measurements were deployed. These sites were sampled for suspended sediment analysis 14 times between 2015-2019 to aid with calibration of the turbidity measurements made using the sondes. Two types of quality-control samples were collected for this study, replicates and blanks. Field replicate samples (FREPs) were collected with approximately 10 percent of the regular environmental samples to evaluate the reproducibility of the entire sampling and analysis process. In addition, laboratory splits of approximately 13 percent of the regular environmental samples were analyzed to evaluate the reproducibility of just the analysis process. See Data Dictionary and the process step on quality control for description of methods used to evaluate replicates. A total of 63 blanks were collected. Most were equipment blanks, but source-solution and field blanks were also collected. See Data Dictionary and the process step on quality control for description of evaluation of results from blanks. Not all the data collected could be stored in NWIS. Column N in the data dictionary lists all the NWIS parameter codes used in this study. Constituents without a parameter code cannot be stored in NWIS. All samples were collected following the U.S. Geological Survey National Field Manual (U.S. Geological Survey, 2018) (see Data Dictionary for detailed information). 2024 Charles N Alpers U.S. Geological Survey, SOUTHWEST REGION Research Chemist mailing address

6000 J Street Placer Hall

Sacramento CA 95819 US 916-278-3134 916-278-3070 cnalpers@usgs.gov Analysis: Samples were analyzed by seven laboratories and additional analyses were also made in the field by staff from the U.S. Geological Survey, Southwest Region, California Water Science Center. See Data Dictionary for references and detailed information for the methods used. Not all samples were analyzed for all constituents. The seven laboratories used were: 1) Hydrologic Research Laboratory, Sacramento, CA (USGSHRCA) 2) Organic Matter Research Laboratory, Sacramento, CA (USGSOMCA) 3) Sediment Analysis Laboratory, Santa Cruz, CA (USGSSDCA) 4) USGS Stable Isotope Laboratory, Menlo Park, CA (USGSMPSIL) 5) USGS Mercury Laboratory, Menlo Park, CA (USGSBGCA) 6) USGS Southwest Isotope Research Labs, Fort Collins, CO (USGSSIRF) 7) USGS National Water Quality Laboratory, Denver, CO (USGSNWQL) The data dictionary identifies which laboratories were used for all constituent analyses and provides link to the published analytical methods. 2024 Quality control: Environmental data review: WQ-Review (v2.2), a toolbox for discrete water-quality data review and exploration, was used to evaluate the environmental dataset stored in NWIS. This tool was used to look for outliers or other suspect values. As the data release was compiled, potential abnormal values were reviewed for potential qualification or rejection by the project chief. Some field parameters were rejected on the basis of incomplete or unclear field or instrument calibration notes which lead to uncertainty in measurement accuracy. Some values (field and laboratory) were rejected for being outliers with respect to historical observations. Values requiring qualification or rejection were addressed by adding field remark comments to NWIS and applying appropriate value qualifier codes. This data release also provides the value-qualifier codes entered into NWIS by the analyzing laboratories. Most of these codes do not result in rejection of data but are included for completeness. The laboratory value qualifier codes and the value qualifier codes added during preparation of this data release are noted in the QA column next to value result column in the data tables. Value qualifier codes and result rejection code definitions are presented in the data dictionary. Value-qualifier codes that resulted in rejection of data are discussed in this process step. Reporting levels and associated value-qualifier codes: Tables T1_Water_Quality, T3_Size_Fraction, and T5_Blanks include information about reporting levels and associated value-qualifier codes for every analytical result, if available. Reporting levels for many analytes changed during the period samples for this study were analyzed, and individual results may have raised reporting levels if samples were diluted for analysis as indicated by a value-qualifier code for dilution. Many laboratories use a laboratory reporting level (LRL or RL) and method detection level (MDL) convention, with results between the RL and MDL assigned a value-qualifier code and results below the MDL reported as nondetections. The result-level value-qualifier codes are described in the Data Dictionary and are reported on tables T1, T3, and T5 in columns labeled “QA” or “quality assurance” immediately following the column for each analyte. Tables T1, T3, and T5 also have columns for each type of reporting level associated with each analyte. Hold-time violations for data in table T1_Water_Quality: Results for samples analyzed past the holding time specified in the analytical method are marked with a value-qualifier code of @ in the QA column associated with the analyte. The 30 results with hold time violations for chlorophyll-a and pheophytin-a were rejected because these analytes may degrade. The 10 results with hold-time violations for chloride and sulfate were not rejected because these analytes are unlikely to degrade. All 519 results for alkalinity in regular and FREP samples were assigned hold-time violation codes because the analyses were made after shipment to the laboratory rather than immediately in the field. However, most were analyzed before the expiration of the hold time for laboratory alkalinity analysis, therefore no data were rejected. Sample preservation violations for data in table T1_Water_Quality: Three water samples for nutrient analysis have value qualifier codes recording that the samples arrived at the laboratory warm rather than chilled as specified in the sample handling protocols. Results for all nitrogen species, particulate nitrogen, particulate inorganic and organic carbon these three samples were rejected because these analytes are more likely to be reactive in warm samples; data for phosphate were not rejected. Eight additional samples for analysis of total particulate nitrogen, and particulate inorganic and organic carbon have value qualifier codes indicating samples arrived warm; these data were rejected. Chlorophyll-a and pheophytin-a data for three samples were also rejected for arriving warm. Rejection of anomalous results for data in table T1_Water_Quality: Two suspended sediment concentration results were rejected because the data failed QAQC evaluation. The ratio of methyl mercury to total mercury was used to check the internal consistency of mercury concentration results, and samples with anomalous ratios were evaluated for possible rejection of data; unfiltered methyl mercury results from one batch of 18 samples in 2010 were rejected. Data for total suspended solids (TSS) and selected particulate mercury species were rejected for one sample because material was likely lost during the sample preparation process. For samples with measurements of field and laboratory specific conductance (SC), 12 percent were outside of the acceptable limit of 20 percent relative percent difference. Comparison between specific conductance and sum of chloride, sulfate, and alkalinity in milliequivalents per liter for the subset of samples that had data for major anions was used to estimate whether field or laboratory specific conductance measurements may be the source of discrepancy. For samples with major anion data, all laboratory SC values were within 10 percent relative percent difference of the value predicted from linear regression between sum of anions and laboratory SC, whereas 12 percent of the field SC values had greater than 10 percent relative percent difference of the value predicted from linear regression between sum of anions and field SC. This suggests that the field SC measurements may be the source of the discrepancy. However, there were fewer laboratory SC measurements than field SC measurements, so the difference may reflect conditions not represented by using major anions as a proxy for salinity. Calibration records for field instrumentation were not available for many of the field SC measurements, therefore quality assurance could not be evaluated. No SC data were rejected, although users are advised to use laboratory SC values for samples for which both laboratory and field SC values are available. Rejection of anomalous results for data in table T4_SS_Weir: Field continuous data were rejected for seven samples and suspended sediment concentration for one sample because the data failed QAQC review. Eight suspended sediment fine material results and one discrete field turbidity result were also rejected because of failed QAQC review. Replicates: Field replicates (FREP) were collected for 56 regular samples and 71 samples were analyzed in duplicate (laboratory replicate, LREP). Not all analytes were analyzed on all replicate samples. Results for FREP and LREP are listed with the results for regular samples in tables T1_Water_Quality, T2_Grain_Size, and T3_Size_Fraction. Additionally, results for replicate analyses of samples not associated with this project but analyzed in the same laboratory batches as samples from this project were compiled from internal lab QC results (analytical replicates, AREP). Summary statistics of the replicate results for FREP, LREP, and AREP by analyte, are presented in the table T6_QAQC. The summary statistics compiled were the median and mean of the absolute deviation, the median and mean of the relative percent deviation, the standard deviation of absolute deviation, and the standard error of relative percent deviation. Replicates pairs with both values less than the MDL or with one value less than the MDL and the other less than the RL were excluded from calculation of relative percent deviation. No data were censored or qualified based on results for replicates. Matrix Spikes: Laboratory analyses for total and methyl filtered and particulate Hg included analysis of matrix spikes (MS) to assess analytical accuracy. Median recoveries for MS are summarized in table T6_QAQC. All median recoveries were within acceptable ranges and no data were censored or qualified based on MS results. Reference Materials: Laboratory analyses for total and methyl filtered and particulate Hg, grain size, stable isotope ratios, and particulate N and P include analysis of reference materials (RM) to assess analytical accuracy. Median recoveries for RMs are summarized in table T6_QAQC. All median recoveries were within acceptable ranges and no data were censored or qualified based on RM results. Blanks: The study collected 55 equipment blanks, 5 field blanks, and 3 source-solution blanks. Blank sample results are presented in table T5_Blanks. Summary statistics of the blank results (percent detected at any concentration, percent greater than the method detection limit, and the percent greater than the reporting limit are presented in table T6_QAQC. Not all analytes were analyzed for all blank samples. All blank samples used deionized water produced in the USGS California Water Science Center Trace Metals laboratory in Sacramento, California. For field blanks, blank water was transported to a field site in carboys and field blanks were collected at field sites by pouring or pumping blank water through the full sequence of equipment used for sample collection. Source-solution blanks consist of blank water poured directly into sample bottles without passing through sampling equipment. Equipment blanks were collected at USGS California Water Science Center Trace Metals laboratory in Sacramento, California by pouring or pumping blank water through sampling equipment. Commonly these equipment blanks were designed to test only one step of the sampling collection process, for example, just the jerricans used to hold samples or just the churns used to split samples. Some equipment blanks tested the whole sequence of steps. Not all equipment blanks, especially those collected before 2016, had sufficient metadata for determining what step of the process was being tested. Many of the equipment blanks were collected to assess the efficacy of cleaning procedures or to assess the readiness of new equipment before it began to be used for sample collection. Cleaning procedures or equipment were modified in response to the equipment blank results before the equipment was used in the field. Therefore, the equipment blanks are not considered representative of the conditions under which samples were collected and are not used to censor data. Because only 5 field blanks were collected, there are insufficient data to determine whether any censoring may be needed based on systematic detections in field blanks. No data were censored based on detections in blanks. 2024 Albers Conical Equal Area 29.5 45.5 -120.0 23.0 0.0 0.0 coordinate pair 0.6096 0.6096 meters North American Datum of 1983 (NAD 83) Geodetic Reference System 1980 6378137.000000 298.257222 Data_Dictionary (.xlsx and .txt) See overview. Producer Defined Table_Number Unique numerical value added to the label of each data table presented in this data release. Producer Defined 1 6 Table_Name The name assigned to each data table presented in this data release. Producer Defined See overview. Table_Column Unique column letter assigned by excel. Producer Defined Each column containing values in an excel table has a unique letter assigned to it. The 1st column in the table begins with the letter "A". Each subsequent column in the table is then assigned the next alphabetical value. If the table length goes beyond the letter "Z" the next column letter is "AA" and the sequence begins again with subsequent columns assigned the next alphabetical value with a preceding "A". So after "AA" the next column is names "AB". This sequencing is repeated until there are no new columns with data. Column_Heading Short label given to each column containing data. Producer Defined Variable. See data dictionary or associated table. Column_Description Detailed description of the short column heading. Producer Defined Variable. See data dictionary or associated table. Extended_Description_Column In some cases and extended description or additional details are provided in this field. Producer Defined -- No Data Producer defined Variable. See data dictionary or associated table. Minimum_Value Minimum value of the range if the column has numeric data. Producer Defined -- No Data Producer defined Variable. See data dictionary or associated table. Maximum_Value Maximum value of the range if the column has numeric data. Producer Defined -- No Data Producer defined Variable. See data dictionary or associated table. Unit_Abbreviation Shorthand abbreviation of a unit of measure. Producer Defined -- No Data Producer defined Variable. See data dictionary or associated table. Unit_Definition Definition of the unit of measure. Producer Defined -- No Data Producer defined Variable. See data dictionary or associated table. Additional_Notes Additional information and or notes to help with the interpretation of what is being presented. Producer Defined -- No Data Producer defined Variable. See data dictionary or associated table. Analytical_Laboratory_Name Full name of the analytical laboratory used for a given analyte or measurement. Producer Defined -- No Data Producer defined Variable. See data dictionary or associated table. Analytical_Laboratory_Location Location of the laboratory used for a given analyte or measurement. Producer Defined -- No Data Producer defined Variable. See data dictionary or associated table. NWIS_Parameter_Code 5-digit code used by USGS to identify the parameter in the USGS National Water Information System (NWIS) database (U.S. Geological Survey, 2024) Producer Defined -- No Data Producer defined Variable. See data dictionary or associated table. NWIS_Method_Code Unique code used by USGS to identify the measurement method in the USGS National Water Information System (NWIS) database (U.S. Geological Survey, 2024). Producer Defined -- No Data Producer defined Variable. See data dictionary or associated table. Method_Reference_Primary Primary reference to published work supporting the analytical method. Producer Defined -- No Data Producer defined Variable. See data dictionary or associated table. Method_Reference_Secondary Secondary reference to published work supporting the analytical method. Producer Defined -- No Data Producer defined Variable. See data dictionary or associated table. T1_Water_Quality (.xlsx and .txt) See overview and data dictionary. Producer Defined T2_Grain_Size (.xlsx and .txt) See overview and data dictionary. Producer Defined T3_Size_Fraction (.xlsx and .txt) See overview and data dictionary. Producer Defined T4_SS_Weir (.xlsx and .txt) See overview and data dictionary. Producer Defined T5_Blanks (.xlsx and .txt) See overview and data dictionary. Producer Defined T6_QAQC (.xlsx and .txt) See overview and data dictionary. Producer Defined CCSB_MAP_USGS2024_CC0.jpg Map showing the locations of sites included in the Cache Creek Settling Basin (CCSB) Project. Two CCSB sites (Cache C at Rumsey and Cache C at Yolo) aren't shown on this map. They are located upstream of CCSB Inlet at Rd 102. Producer Defined This data release includes 7 tables provided as machine-readable tab-delimited text (*.txt) files and as Excel formatted (*.xlsx) files. Tables 1-4 all share some common information such as, but not limited to, location information (latitude and longitude), sample collection date and time, sample and site type, site and field name, and discharge information. Null values, empty cells with no value, are denoted with a -- symbol. 1) ‘Data_Dictionary’, the Data Dictionary, which provides definitions and details related to the other six data tables and includes citations of analytical methods; 2) ‘T1_Water_Quality’, the discrete-sample surface-water dataset including concentration data for Hg species (including total mercury and methylmercury in dissolved and particulate forms) and nutrients (including several forms of nitrogen and phosphorus); 3) ‘T2_Grain_Size’, detailed grain size distributions presented as percentages of clay, sand, and silt (Coulter counter); 4) ‘T3_Size_Fraction’, suspended sediment size fraction data for particulate total mercury and particulate carbon and nitrogen; 5) 'T4_SS_Weir', suspended sediment and turbidity data collected at the Cache Creek overflow mid weir locations; 6) 'T5_Blanks', compiled blank data and; 7) 'T6_QAQC', summary statistics of field, laboratory, and analysis replicates, and some additional blank results. Alpers, C.N., Miller, S.L., Agee, J.L., Marvin-DiPasquale, M.C., Kieu, L.H., Kakouros, E., Hansen, A. M., Fleck, J.A., Ward, A.J., Watanabe, P.T., and Bennett V, G.L., 2025, Water-quality data including mercury and methylmercury at selected sites in the Cache Creek watershed, Yolo County, California: U.S. Geological Survey data release, https://doi.org/10.5066/F70R9N9H GS ScienceBase U.S. Geological Survey mailing address

Denver Federal Center, Building 810, Mail Stop 302

Denver CO 80225 United States 1-888-275-8747 sciencebase@usgs.gov Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data on any other system or for general or scientific purposes, nor shall the act of distribution constitute any such warranty. Digital Data https://doi.org/10.5066/F70R9N9H None 20250411 Shanna L. Miller U.S. Geological Survey, SOUTHWEST REGION Hydrologic Technician mailing address

6000 J Street Placer Hall

Sacramento CA 95819 US 916-278-3036 slrmiller@usgs.gov FGDC Biological Data Profile of the Content Standard for Digital Geospatial Metadata FGDC-STD-001.1-1999