Arroyo Seco GSA approves rural-well water-quality study, hears update on demand-management planning

The Arroyo Seco Groundwater Sustainability Agency on Thursday approved a study compiling locations and water-quality data for rural domestic wells across the Forebay and portions of the Upper Valley, and received a report from the general manager about upcoming updates to the groundwater sustainability plan and possible demand-management steps.

The study, prepared by consultant Gus Yates and summarized to the board by General Manager Curtis Weeks, maps hundreds of rural domestic wells and analyzes concentrations of constituents including nitrate, chloride, sulfate, total dissolved solids and a single detection of 1,2,3-trichloropropane (TCP). Weeks told the board the study is "pretty much what we expected," and said the work will be routed to the Salinas Valley Basin GSA as a management action for inclusion in the basin's submittal to the California Department of Water Resources.

The study matters because the board found clusters of elevated nitrate around the City of Greenfield and near King City; the board highlighted nitrate's 45 milligrams-per-liter maximum contaminant level (MCL) as the principal regulatory concern. The consultant and staff recommended the inventory be used to identify local consolidation or targeted solutions, and noted…