Two currently used herbicides are found in more than half of the streams sampled in agricultural areas. No pesticide was found in more than one-third of ground water samples. The lines indicate that more samples contained one pesticide than had two pesticides, and so on. These graphs show the amounts detectable using current screening methods. These maps show the locations of ground water study areas and stream sampling sites in agricultural areas.
Samples shown here are from areas indicated on the maps above .
All compounds are in current use, with the exception of deethylatrazine, which is a breakdown product of atrazine. Stream samples are intended to represent common conditions during seasons with significant runoff. However, USGS recommends further assessment of edible species if there are active fisheries in streams where high concentrations were found. Please see the Technical Notes for additional information.