While atrazine remains one of the most frequently detected herbicides in water supplies in the US, the high frequency of detection is partially attributed to an increase in the sensitivity of analytical methods used to detect atrazine.
The levels detected in the last ten years have usually been lower than the Maximum Contaminant Level (MCL) allowed in drinking water.
But, there is concern that atrazine levels in water of some areas, especially agricultural areas, is still in the 10-20 microgram per liter range. In a recent study over five percent of the water samples from agricultural areas had atrazine levels that exceeded the 3.0 micrograms per liter, the Maximum Contaminant Level for atrazine in drinking water. Levels as high as 120 micrograms of atrazine per liter were detected in this study.