Evaluating the Effectiveness of Ground Water Protection Regulations

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Back to Identifying and Protecting Ground Water Protection Areas

In 1999, DPR established a network of shallow domestic wells in Fresno and Tulare counties to assess the effectiveness of pesticide use restrictions enacted to protect groundwater from further contamination by pesticide residues.

DPR first developed regulations for use of pesticides detected in groundwater in the late 1980’s. Use was regulated in areas denoted as Pesticide Management Zones, which were sections of land where DPR detected residues of atrazine, bromacil, diuron, norflurazon, prometon and simazine in well water. DPR revised the ground water protection regulations in May of 2004, to create Ground Water Protection Areas and adopt pesticide use restrictions based on the pathway and mechanism by which a pesticide might reach ground water.

DPR, in collaboration with the U.S. Geological Society, determined that it took seven to nine years for an herbicide to reach groundwater from the time it was applied to the soil. Since the new regulations went into effect in 2004, DPR intends to continue sampling the wells in this network until concentration trends can be detected and the regulations’ impacts can be determined.

Well network study:

Related research:



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