Salinas River Watershed Area Salt Modeling

Tetra Tech supported EPA Region 9 and the Central Coast Regional Water Quality Control Board (CCRWQCB) for an assessment of salt impairments and development of a salt mass balance in the Lower Salinas River and Reclamation Canal watersheds. This effort can inform development of salt-related TMDLs by the CCRWQCB and a salt and nutrient management plan for the Salinas Valley aquifers. Three reaches have reported 2010 303(d) listings for salt-related impairments in these watersheds including impairments due to chloride, sodium, electrical conductivity, and total dissolved solids – Lower Salinas River, Santa Rita Creek, and Alisal Creek. This report provides data analysis and a literature review (Sections 1 through 5), development of a water and salt mass balance tool (Sections 6 through 8), and salt source assessment (Section 9). The results of the analysis provide a strong foundation for assessing salt sources and understanding salt mass balance in the study area, but can be improved with refined representation of cropland locations, rotations, and irrigation practices.