It is critical that every effort be made to protect ground water quality. Irrigation wells can be constructed and maintained to assure that ground water quality is protected. Improperly constructed or maintained wells can allow bacteria, pesticides, fertilizers, oil products or other pollutants to contaminate ground water.
Several factors make irrigation wells vulnerable to potential contamination. Wells are located adjacent to or in cropland areas. This means that there is a high probability agricultural chemicals, pesticides and fertilizers will be applied near the well. It is important that the well construction be such that agricultural chemicals cannot reach the aquifer directly down the well or around the well casing. Past irrigation well construction methods have not been as protective of water quality as provided by current construction regulations.
Many irrigation wells are pumped using an internal combusting engine, which means fuel and oil products are used at the well site. A spill of petroleum products at the well site could result in significant ground water contamination. Application of chemicals through the irrigation water (chemigation) has become a common practice. Backflow or backsiphonage during chemigation without the proper safety equipment can allow chemicals to flow down the well directly into the ground water.
There are many potential sources of contamination at an irrigation site. Preventing contamination at an irrigation well is important. Once ground water is contaminated, it is very difficult and costly to clean up. Contamination will move with ground water and eventually can reach domestic water supply wells.