Groundwater that meets drinking water standards for nitrate and arsenic protects human health.

The Measure

Groundwater meets drinking water quality standards in the Delta for nitrate and arsenic. 

  • Expectations

    Drinking water quality for residents in the Delta is improved to meet standards for nitrate and arsenic.

  • Performance Metrics

    • Number of groundwater wells used for drinking water supply that exceed arsenic and/or nitrate drinking water limits, evaluated every five years.

Number of sampled groundwater wells used for drinking water supply that have exceed or exceeding arsenic and/or nitrate drinking water limits

The number of sampled public groundwater wells in the Delta exceeding or that have exceeded nitrate and arsenic standards should be less than 50 percent of the 2001—2013 baseline values by 2034.

Disclaimer

Individual wells that violate certain drinking water standards may not pose a threat if the water system has the ability to blend the groundwater with other supplies to meet standards. Private well owners are not represented in the total number of wells shown above.

Sampling

The collection of samples may be inconsistent or have been discontinued. A well sampled during the baseline time period (2001-13), may not have been sampled again in the following evaluation time period (2014-18), which can reduce the number of wells.

Groundwater wells used for domestic and municipal water supply that exceed arsenic and/or nitrate drinking water limits in the Delta are water quality issues and are possible indicators of other more serious contaminants. This is especially true for small water systems and disadvantaged communities that are highly dependent on groundwater sources that may not meet certain drinking water quality standards. Sources of nitrate and arsenic contamination can come from both natural and man-made sources. Consumption of high levels of nitrate and arsenic have various long and short term health effects.

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 drinking water quality

Delta Plan Recommendations

  • Complete central valley drinking water policy
  • Complete North Bay Aqueduct Alternative Intake project
  • Protect groundwater beneficial uses
  • Participation in CV-SALTS
Metric
  • Number of groundwater wells used for drinking water supply that exceed arsenic and/or nitrate drinking water limits, evaluated every five years.
Baseline
  • Number of wells within the Delta which exceed 2008 California water quality standards for levels of nitrate not to exceed (10 ppm NO3-N) and arsenic not to exceed (10 ppb As) between the years of 2001 and 2013
Target
  • A 50 percent reduction in number of wells exceeding nitrate and arsenic standards from baseline levels using historical data (2001-2013), by 2034.

Data is retrieved from the State Water Resources Control Board's Groundwater Ambient Monitoring and Assessment Program (GAMA). The tool can filter different types of contaminants and their concentrations, time of sampling, and locations. Data is then filtered by collecting the locations of wells within the Delta.

The data above was filtered only for Public Water System Wells category in GAMA.

Data Source:

Groundwater Ambient Monitoring and Assessment Program (GAMA)

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