Although some recent national studies suggest that agriculture may be causing increased levels of pesticides in rural drinking water wells, there is little evidence that is occurring in Texas. However, dairy operations and nutrient applications to croplands are contributing to increased levels of fecal colifomm bacteria and nitrates in surface and ground waters. Contaminants that were found include sediments, chlorides, sulfates, phosphorus, nitrogen, nitrate, total dissolved solids, fecal coliform bacteria, trash and debris, fertilizers and pesticides, and heavy metals such as mercury and lead.
Little information is known on groundwater contamination by synthetic organic chemicals.
In contrast, only 14,000 tons of pesticide were sold. Some pesticides were not detected in follow-up studies. Many of the problems stemmed from point source contamination of wells and wellhead areas. Groundwater quality testing was also conducted in the Ogallala Aquifer by the High Plains Underground Water Conservation District No. 1 in 1987. When followup tests were conducted 1988, these pesticides could no longer be detected.