Water quality in the Delta and Suisun Marsh meets the standards of the Clean Water Act.
Reduction of Delta waterbodies on the 303(d) list to achieve the protection of beneficial uses in the Delta.
The number of Delta watershed waterbody contaminant combinations on the 303(d) list, evaluated every eight years.
Next Data Update: Data will be updated soon after the approval of the integrated report by the United States Environmental Protection Agency. The next full assessment update of the 303(d) integrated report for the Central Valley will be in 2028.
Consistent good water quality is crucial for successful restoration efforts of aquatic habitats and other beneficial uses of Delta water. High amounts of pollutants, or other water quality issues, can impair the ability of water to support beneficial uses, such as: recreational use, agricultural water supply, municipal water supply, and healthy habitat for native vegetation and wildlife. Reduction of impaired water bodies on the 303(d) list of the Clean Water Act is important for the protection of beneficial uses in the Delta.
The Clean Water Act (CWA) protects and restores surface water quality by regulating pollutants and quality standards for the waters of the United States. The State Water Quality Control Board (SWRCB) and its regional boards evaluate surface water quality data and develop a list of waters that do not meet established water quality standards (impaired waters) and those that currently meet water quality standards but may exceed it in the next reporting cycle (threatened waters).
The 303(d) list contains the waterbody name and the type of contaminant in the waterbody. A waterbody can contain several combinations of contaminants. The 303(d) list is evaluated every two years to determine if waterbodies meet the water quality standards. Polluted waters continue to be monitored and assessed until applicable water quality standards are met. The SWRCB issues integrated reports with updated 303(d) water bodies list.
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
- Require Delta-specific water quality protection
Delta Plan Recommendations
- Protect beneficial uses
- Identify covered action impact
- Special water quality protections for the Delta
- The number of Delta watershed “waterbody-contaminant” combinations on the 303(d) list, evaluated every eight years within the State Water Resources Control Board (SWRCB) Integrated Report
- Measured as of the 2010 SWRCB Integrated Report
- Reduction of 40 percent of the “waterbody-contaminant” combinations on the 303(d) list by 2034
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-contaminant combinations in the list.
- Then compared it to the previous integrated report (baseline).
Example of waterbody-contaminant combination: Water Body Name paired with the type of pollutant. A waterbody can be listed more than once if it contains several pollutants.