Reclamation Information Sharing Environment (RISE)

This is the final report for the special study "Exploring Flow and Water Quality Relationships Between the Interior Southern Delta and the San Joaquin River at Vernalis." This study uses publicly available observations of flow and salinity concentrations at key regulatory monitoring locations on the lower San Joaquin River and the interior southern Sacramento-San Joaquin River Delta for Water Years 2006 to 2024. Different subsets of the data are used to explore simple linear regressions between the San Joaquin River at Vernalis and salinity concentrations downstream on Old River near Tracy to evaluate the conditions in the San Joaquin River Basin under which water quality objectives downstream on Old River are met and whether these conditions are predictable. During dry conditions in the San Joaquin Basin, when flows are low and salinity concentrations are typically higher in the southern interior Delta, no predictive relationship is found between Vernalis and Old River, suggesting that other variables exert more influence on Old River salinity during these times.