A Spatially Varied Index Method to Define Relative Risks Associated with Pesticide Contamination of Groundwaters

B. T. Daniels
W. F. McTernan

DOI: 10.2190/06FQ-E7CB-434Y-5DQA


In order to assess groundwater contamination from pesticides, a method was developed and applied to a large section of the state of Oklahoma. The method, which is titled the PESTICIDE RISK INDEX, used the DRASTIC Index along with pertinent data defining Oklahoma's hydrogeological and agricultural conditions to identify areas with the potential for contamination. The probability and extent of leaching for various soil and pesticide combinations found in Oklahoma were defined with a Monte Carlo analysis of 540 years of simulated field conditions using the Pesticide Root Zone Model (PRZM). The risk of human exposure to contaminated sources of drinking water was assessed by consideration of the Environmental Protection Agency's Reference Doses for selected pesticides, and the groundwater usage statistics for Oklahoma. The Index resulted in a series of maps which identified the locations of greatest relative susceptibility.

The Pesticide Risk Index identified three areas of Oklahoma with potential high risk for exposure to pesticide contaminated groundwater. The Monte Carlo analysis indicated that certain site and chemical pairings could result in significant leaching. It was found that soil retardance was the most determinant factor in the leaching of pesticides.

Creative Commons License This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 United States License.