The Department of Pesticide Regulation (DPR) has found that specific combinations of soil types and depth to groundwater are common to areas where pesticides have been found in groundwater due to routine agricultural uses. DPR then designated all sections of lands in California with similar features as ‘groundwater protection areas (GWPAs). To carry out DPR’s mandate to prevent further pollution of groundwater, users of 6800(a) pesticides are regulated in GWPAs.

GWPAs are geographically defined areas that are vulnerable to pesticide contamination by leaching or runoff. GWPAs include all existing pesticide management zones (PMZs), plus other areas based on specified soil types, and a depth to groundwater of 70 ft or less.

Leaching GWPAs are defined as sections of land where pesticide residues move downward from the application site on the soil surface through the soil matrix with percolating water to groundwater. Leaching GWPAs are located in areas with coarse-textured soils that have rapid infiltration rates.

Runoff GWPAs are defined as sections of land where pesticide residues are carried in runoff water from application sites to more direct routes of groundwater recharge such as dry or drainage wells, poorly sealed production wells, ditches or retention areas excavated below confining soil layers, or to areas where leaching can occur. Soils in runoff GWPAs have low infiltration rates caused by a hardpan layer or fine-textured soils.

Location of GWPAs
DPR has prepared maps for each county, showing the sections designated as leaching GWPAs and the sections designated runoff GWPAs. These maps are available on the following website:

http://www.cdpr.ca.gov/docs/empm/gwp_prog/gwpamaps.htm

I've checked and I want to use of of the listed pesticides in a:
Leaching GWPA - What do I need to do?
Runoff GWPA - What do I need to do?