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Planned upgrades to the Sacramento Regional wastewater treatment plant (SRWTP) will substantially reduce nutrient discharge and also alter the types and amounts of nutrients being distributed across the San Francisco Delta and Estuary (Delta).
One highly anticipated outcome of lower nutrients is improved productivity in the phytoplankton communities that supply aquatic food webs, which should improve conditions for declining pelagic fish species. Reductions in the occurrence of harmful algal blooms and associated cyanotoxins is another possible beneficial outcome of the planned upgrades.
Assessing the relationships between the distribution of nutrients and phytoplankton under different conditions across the Delta is the best means to understand how managing nutrient supplies affects aquatic food webs. Knowing more about how nutrient management affects aquatic food webs will help managers evaluate the potential environmental benefits of future nutrient reduction efforts against the costs.
This project will evaluate the effects of wastewater-derived nutrients on the phytoplankton community by employing three complementary approaches.
Boat-based Mapping Survey
The first approach is a novel high-resolution, boat-based mapping survey system that provides spatial information over large regions for a specific time period (e.g. 4 consecutive days of data collection). This produces, for example, high-resolution maps of ammonium, nitrate, phytoplankton abundance, phtytoplankton community composition, and water quality (temperature, specific conductance, turbidity, dissolved oxygen, etc.).
Continuous Monitoring Stations
In the second approach, the USGS will enhance existing continuous monitoring stations in the Delta, making them capable of monitoring not only phytoplankton abundance but also the types of phytoplankton present in the water column. This data will be available every 15 minutes in real time, producing a continuous times series of data to permit examination of any changes over time.
The third approach will be to collect discrete samples during the mapping surveys at approximately 30 locations across the Delta and at the continuous monitoring stations at least monthly. These samples will be analyzed for nitrate, ammonium, phosphate, total dissolved nitrogen, dissolved organic carbon, chlorophyll-a, phaeophytin, phytoplankton enumeration, picoplankton direct counts, and cyanotoxins.
The timeline for the collection of data will span from the spring of 2020 to the fall of 2021. Over the course of the study, both mapping survey data and data collected at fixed stations will be shared as it becomes available. A synthesis of study results will be presented at conferences and stakeholder meetings as appropriate. Final data from the mapping surveys will be published as a product on the USGS Science Base data repository, and data from the fixed stations published on NWIS. We will also make the data analysis and visualization tools we use for preparation of the synthesis publicly available online together with the data to make it possible for stakeholders, researchers and managers to explore the data themselves and download portions for further analysis.
Below are other science projects associated with this project.
Preliminary Data Release for 2020 Study:
Assessing spatial variability of nutrients, phytoplankton and related water-quality constituents in the California Sacramento-San Joaquin Delta at the landscape scale: 2020 High-resolution mapping surveys
Data from previous studies are listed below.
Data visualization tool created for California's Bay-Delta Regional Monitoring Program. This web applicaton visualizes nutrients and phytoplankton spatially and temporally.
A data visualizatoin exploring the relationship between nutrient distribution and phytoplankton under different conditions across the San Francisco Delta and Estuary. Assessing distribution and abundance aids understanding of how managing nutrient supplies affects aquatic food webs, helping managers evaluate the potential environmental benefits of future nutrient reduction efforts against costs.
Data visualization tool created for California's Bay-Delta Regional Monitoring Program. This web application visualizes nutrients and phytoplankton spatially and temporally for data collected in 2018.
Below are partners associated with this project.