Groundwater Monitoring, Analyses, and Assessments
DPR’s Groundwater Protection Program (GWPP) obtains groundwater monitoring data for pesticides and their degradates through its own sampling program and from sampling conducted by other public agencies. DPR’s Human Health Assessment Branch evaluates and determines risk based on the data.
DPR's GWPP monitors groundwater to determine (1) whether pesticides with the potential to pollute groundwater are present in groundwater, (2) the extent and source of pesticide contamination, and (3) the effectiveness of regulatory mitigation measures.
DPR and Multi-agency Data
DPR’s GWPP also compiles pesticide-related groundwater monitoring data from other public agencies in California and enters the data into DPR’s Well Inventory Database annually. DPR evaluates all reported detections and often conducts follow-up sampling to confirm detections reported by other agencies. These data are reported yearly in the Annual Well Sampling Report along with the actions taken by DPR and the State Water Resources Control Board to protect groundwater from contamination by agricultural pesticides.
- Well Inventory Database – all wells sampled for pesticides in California
- Annual Well Sampling Report – Sampling for Pesticide Residues in California Well Water
- Policy on the release of well sampling data
Drinking Water Standards and Pesticide Use Information
The following fact sheets contain information about pesticides or degradates that DPR’s GWPP actively samples for or has sampled for in the past. Many pesticides listed have not been detected in California’s groundwater by DPR.
- Pesticide Information and Use Fact Sheet, June 2022, PDF
- Pesticide Drinking Water Standards Fact Sheet, June 2022, PDF
DPR Human Health Risk Assessments for Groundwater
DPR’s Human Health Assessment Branch has conducted Drinking Water Evaluations for the following pesticides detected in groundwater:
- Dacthal (DCPA) Degradates
- Simazine and degradates
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