CalGW Update 2020 - GW Quality Constituents Detected (2009-2018)

CalGW Update 2020 - GW Quality Constituents Detected (2009-2018) dataset assesses statewide groundwater conditions based on a query of the GAMA database (provided by the State Water Resources Control Board). The original query searched GAMA for the maximum groundwater quality sampling result for each chemical with an established maximum contaminant level (MCL) or secondary maximum contaminant level (SMCL) from January 1, 2009, through December 31, 2018. All stations tagged as monitoring wells for permitted discharge sites, active contaminant investigations, or active cleanup sites were omitted from the dataset. The final queried dataset included more than 5 million records, more than can fit into an Excel spreadsheet, so this dataset was created summarizing water quality conditions in each hydrologic region. This summary includes the number of wells which fall into one of three categories for each chemical with an established MCL or SMCL: High (maximum recorded value above the MCL or SMCL); Medium (maximum recorded value between half the MCL or SMCL and the MCL or SMCL); Low (maximum recorded values less than half of the MCL or SMCL). This dataset was used to create Table 6-6.