High-resolution mapping survey and vertical profiles of water quality, nitrate, and chlorophyll fluorescence in the lower Sacramento River (California, USA)

The Sacramento River supplies most of the freshwater to the Sacramento-San Joaquin Delta (Delta). Phytoplankton are an important food source for zooplankton and pelagic fish in the Delta. Using a boat-based flow-through system, water quality parameters were mapped along the Sacramento River on August 11, 2025. The mapping began at Tisdale Weir, north of Sacramento, and extended approximately 160 kilometers downstream to Isleton, in the Delta. Vertical profiles were also collected at 9 locations to measure vertical variation in water the water column and calculate light attenuation coefficients. Data collected include chlorophyll fluorescence, nitrate, temperature, dissolved oxygen, pH, turbidity, specific conductance, fluorescence of dissolved organic matter, and photosynthetic active radiation (PAR) profiles.