Groundwater Contamination Comes from Many Sources

Groundwater contamination is a strong concern because contaminants travel unnoticed until the water is tested. Once contaminated, an aquifer is difficult and expensive to clean up.

Some sources of contamination occur nationwide, such as septic tank effluents, municipal landfills and leaking underground petroleum storage tanks. Groundwater quality can vary greatly from place-to-place and is determined primarily by the soils, sand, gravel and rock the water has moved through.

Generally the midwest has excellent quality groundwater. But in some areas human activities have caused water quality to decline. Industrial solvents, manufacturing chemicals, fertilizers, ammunition wastes, pesticides, grain fumigants and human and livestock wastes have added to groundwater pollution at some Nebraska locations.

University of Nebraska-Lincoln water scientists Mary E. Exner and Roy F. Spalding concluded in 1990 that nitrate is by far the most frequently encountered health-related groundwater contaminant in Nebraska. Their data was based on well sampling results from state, local and federal agencies. The two UNL researchers found nitrate concentrations exceeded the drinking water standard in groundwater in more than 20 percent of the wells they sampled. Although many of these wells were in areas highly vulnerable to contamination. The commonly used herbicide atrazine was detected in more than 13 percent of the wells sampled, with the vast majority of samples showing only trace levels much below the drinking water standard.

For more details, "Occurrence of Pesticides and Nitrate in Nebraska's Ground Water," is available from the UNL Water Center/Environmental Programs, P.O. Box 830844, University of Nebraska, Lincoln, NE 68583-0844 or call (402)472-3305.