Water quality in the White River Basin is impacted by urban and agricultural activities, according to the results of a five-year investigation by the U.S. Geological Survey (USGS), Department of the Interior.
A variety of pesticides used for agricultural or urban uses were commonly found in streams throughout the White River Basin. In contrast, only a few pesticides were found in ground water, and these were at much lower concentrations. Pesticide concentrations in streams in the White River Basin were among the highest found at USGS monitoring stations nationwide.
Twenty-five different pesticides or pesticide degradation products were found in at least 5percent of samples near the mouth of the White River. The widely used agricultural herbicides atrazine and metolachlor were always found. "In a few samples, concentrations of the herbicides atrazine, alachlor, or cyanazine exceeded Federal drinking-water standards or advisories; however, annual average concentrations of each of these compounds in the White River were below their respective standard or guideline," said USGS hydrologist Charles G. Crawford, project leader of the White River Basin study.
Fourteen different pesticides were found in a network of 94 shallow
monitoring wells; six were found more than once. However, Crawford said,
"No pesticide concentration found in ground water came close to exceeding
a Federal drinking-water standard or advisory." In cropland areas with a
surficial sand and gravel aquifer that is particularly vulnerable to
contamination but is also an important source of drinking water for
residents of the basin, atrazine compounds were found in two-thirds of
monitoring wells but only at trace levels. Shallow wells are most
susceptible to contamination and provide insight into the effects of
pesticides and fertilizers on ground-water quality. Pesticide
concentrations typically decrease with depth in an aquifer. The presence
of only low pesticide
Contact: Charlie Crawford
United States Geological Survey