New regs will alter state irrigation

Increased training and reporting to affect growers, PCAs The water supply and regulation landscape is changing fast in California. The development of new regulations for "Groundwater Protection Areas" (GPAs) by the California Department of Pesticide Regulation (DPR) over the next few years will significantly change irrigation and pesticide application practices in some areas.

GPAs will replace the older Pesticide Management Zones (PMZ) established by DPR during the last decade. The total number of GPAs will be many times greater. than the old PMZs. This is a major shift in regulatory focus across California. DPR examined similarities in soil type, depth to groundwater and farming practices/crop rotation in areas where some pesticide contamination of groundwater exists. The idea is to proactively designate areas that match these characteristics as a GPA.

The PMZs now in existence were established only after one or more pesticides were found in well water in that area.

Training, reporting The proactive stance for protecting groundwater resources in areas with sensitive aquifers is admirable and probably long overdue. The bottom line, however, means increased training and reporting requirements for growers and pest control advisors using certain herbicides and insecticides in these GPAs. The full extent of these requirements will slowly unfold over the next three to four years. Some type of irrigation record keeping (made available to the county ag commissioner) will almost certainly be part of the scenario.

Agricultural wellhead protection measures and irrigation system backflow prevention will be required by fall 2001. Some research gaps exist and DPR is cooperating with the University of California Cooperative Extension and the Cal State University's Center for Irrigation Technology (CIT, Fresno) and Irrigation and Training Research Center (ITRC, San Luis Obispo) to fill these voids.

The focus is not to place unbearable regulations on the backs of farmers but develop practical management strategies to minimize the possibility of contamination.

"Chemigation" and "fertigation" through irrigation systems has become much more common around the state in recent years. Of the 420 different active ingredients in pesticides that are labeled for use in California, 109 have at least one product label allowing injection/application through irrigation water. These chemicals can be a source of backflow contamination into surface and ground water. U.S. EPA guidelines on labels that permit chemigation already require backflow prevention.

The new DPR regulations for backflow prevention to be implemented fall 2001 are merely to standardize this equipment for California and verify installation. This should be a "heads up" call for farmers and engineers planning irrigation system projects and improvements for this winter.

Backflow prevention devices will almost certainly be more costly and sophisticated than the gravity `flap-type' valves now commonly installed on wells. CIT, Fresno is in the process of evaluating the wide range of devices now available and their durability in an ag setting. These devices will be required on wells and all irrigation district turnouts, standpipes and gates where there is no air gap between the outlet from the water source into the irrigation system. No additional taps, tees or injection points can be placed between the water source outlet and the backflow preventer.

For new systems being installed this winter: Do not purchase and install a backflow preventer at this time! Chances are you won't get the right one. (If you must inject pesticide this coming season, you have to install some type of backflow preventer to meet label requirements. Check out Idaho State's Web site,, for ideas.) The best advice at this time is to leave a straight section of pipe at least 11 pipe diameters long for 4-inch pipe, 10 for 6-inch, 9 for 8- and 10-inch, and 6 diameters for 12- and 14-inch. This will accommodate any of the devices currently available and make retrofitting with the proper valve easier.

Well heads and pads that may receive agricultural runoff will have to be above grade or have a berm built up that's high enough to withstand flood conditions.

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