Identifying and Protecting Ground Water Protection Areas

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DPR regulates the use of known ground water contaminants in vulnerable areas called ground water protection areas.

  • Identifying ground water protection areas
    How soils and depth to ground water data are used to identify ground water protection areas.
  • Location of ground water protection areas
    Locations of ground water protection areas by county. GWPAs are one-square mile sections of land vulnerable to the movement of pesticides to ground water, via runoff or leaching, based either on pesticide detections or on certain soil types and a depth to ground water shallower than 70 feet.
  • Identifying pathways, mechanisms, and mitigation measures
    DPR has identified runoff and leaching as two pathways to ground water, excess irrigation and rainfall runoff as two mechanisms for moving pesticides to ground water, and mitigation measures to stop or prevent ground water contamination.
  • Pesticide use regulations to protect ground water
    Regulations adopted by DPR to protect ground water from contamination resulting from agricultural, outdoor industrial and outdoor institutional use of pesticides.
  • Evaluating the effectiveness of ground water protection regulations
    Annual sampling in a well network to determine if use restrictions in ground water protection areas are reducing pesticide concentrations in ground water over time.


For content questions, contact:
John Troiano
1001 I Street, P.O. Box 4015
Sacramento, CA 95812-4015
Phone: (916) 324-4115
E-mail: John.Troiano@cdpr.ca.gov