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Scientists Assess Sediment Nutrient Storage and Release in California's Sacramento-San Joaquin Delta

January 29, 2021

California Water Science Center scientists have begun the first comprehensive assessment of sediment nutrient inventories and fluxes in the Sacramento-San Joaquin Delta (Delta). Their findings will serve as a baseline for assessing water quality improvements following upcoming upgrades to the Sacramento Regional Wastewater Treatment Plant and wetland restoration efforts.

Biologist Ethan Enos
Biologist Ethan Enos holds up a core collected in the Delta.​​​​​​​

Sediments represent an important pool of nutrients in the Delta. The exchange of nutrients between the water column and the benthos is an important determinant of water quality and its effect on phytoplankton, harmful algal blooms, aquatic vegetation, and drinking water quality. To date, there is very limited information about nutrients in Delta sediment. This information is needed to inform widescale wetland restoration efforts which are expected to change sediment nutrient inventories, transformation rates and fluxes which will impact Delta habitats. Further, this information is also needed as a baseline prior to the planned reduction in nutrient inputs to the Delta following this year's wastewater treatment plant upgrade by the Sacramento Regional County Sanitation District (Regional SAN). Municipal wastewater accounts for approximately 25% of the total nitrogen loads and 20% of the total phosphorus loads to the Delta. This study is being conducted in close collaboration with researchers at UC Davis who will be using metagenomic approaches to understand the role of the microbial community, including cyanobacteria (which can be harmful algae), in benthic nutrient cycling.

Learn more about this project.