The wellhead protection regulation (California Code of Regulations (CCR) 6609) was added to protect wellheads from pesticide contamination. Among other provisions, this regulation prohibits application of pre-emergent herbicides within 100 feet of unprotected wells (those where water may flow from the area treated to the wellhead, and contact the wellhead). This prohibition was adopted because pre-emergent herbicides are the primary pesticides that have been found in ground water due to agricultural use.
Pre-emergent herbicides that have been found in ground water are both mobile and persistent, which are characteristic of pre-emergent pesticides listed in Title 3 CCR Section 6800(a) and (b) (the Ground Water Protection List). These herbicides are not allowed to be used within 100 feet of an unprotected well. However, some pre-emergent herbicides are not listed in 3CCR section 6800(a) or (b) because they are either not mobile or persistent. Because of this they are considered to have low potential to move offsite to ground water and are allowed to be used within 100 feet of an unprotected well.
For the purposes of the wellhead protection regulation, “pre-emergent herbicides” means pre-emergent herbicides that are listed in 3CCR section 6800(a) or (b):
Pre-emergent Herbicides on 6800(a) List
Atrazine, Simazine, Bromacil, Diuron, Prometon, Norflurazon
Esticides containing a chemical listed in title 3 ccr section 6800(a) when labeled for agricultural, outdoor institutional, or outdoor industrial are designated as restricted materials per title 3 ccr section 6400(d).
All purchases, statewide, must be made by a certified applicator.
All applications, statewide, must be made by or under the direct supervision of a certified applicator. Permits are generally required for restricted materials. However, no permit is required for use of a pesticide listed only in section 6400(d) when used outside of a ground water protection area (gwpa) or when used in a pest eradication program approved by the California department of food and agriculture.