The 2020-2022 update to the 303(d) list shows a 13% net increase of waterbody-pesticide combinations in the Delta and Suisun Marsh.
The Measure
Reduction in the number of critical pesticides in the waters and sediments of the Delta and Suisun Marsh.
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Expectations
Number of critical pesticides in the waters and sediments of the Delta and Suisun Marsh is reduced.
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Performance Metrics
- The number of Delta watershed waterbody-pesticide combinations on the 303(d) list, evaluated every eight years.
Next Data Update: The next update of the 303(d) integrated report is anticipated in 2024. The data above will be updated soon after the release of the integrated report.
An overall reduction of critical pesticides in the waters and sediments of the Delta and Suisun Marsh will be beneficial for ecosystem health and drinking water supplies. The Central Valley Regional Water Quality Control Board (CVRWQCB) Basin Plan sets objectives to control pesticide runoff into Delta waters.
Although pesticides have many uses for agriculture, urban, and residential areas, they also have the potential to contaminate drinking water supplies. Aquatic ecosystems contain species related to the target organisms of pesticides, and undesirable side effects may occur to native and desired species in relation to high pesticide exposure. The California Department of Pesticide Regulation reports that 13,084 pesticide formulations are registered in the state and are of concern to fish and zooplankton health.
Each chapter of the Delta plan includes strategies to achieve the goals of the plan. These strategies are general guidance on achieving the objective laid out in the plan and in the Delta Reform Act of 2009. Associated with these strategies are recommendations. The recommendations describe more specific and implementable actions to support the achievement of Delta Plan strategies. Strategies and recommendations may also have associated performance measures. Delta Plan performance measures track progress in achieving desired outcomes for the Delta Plan. Below are the strategies and recommendations associated with this performance measure.
Delta Plan Strategy
- Improve environmental water quality
Delta Plan Recommendations
- Completion of regulatory processes, research, and monitoring for water quality improvements
- Implement Delta Regional Monitoring Program
Metric
The number of Delta watershed “waterbody-pesticide” combinations on the 303(d) list, evaluated every eight years within the State Water Resources Control Board (SWRCB) Integrated Report.
Baseline
Measured as of the 2010 SWRCB Integrated Report
Target
Zero “waterbody-pesticide” combinations on the 303(d) list by 2034.
Methods
Impaired waterbodies are listed (303(d) List) in the State Water Resources Control Board's Integrated report.
- We downloaded the 303d list and the accompanying GIS file.
- Then used ArcGIS (10.4) to clip the 303d list within the boundaries of the Delta and Suisun Marsh and summed the number of waterbody-pesticide combinations in the list.
- Then compared it to the previous integrated report (baseline).
Example of waterbody-pesticide combination: Water Body Name paired with the type of pesticide. A waterbody can be listed more than once if it contains several types of pesticides.