GEOGRAPHIC DISTRIBUTION OF PESTICIDE CONTAMINATION IN THE ST. JOSEPH RIVER WATERSHED, NORTHEAST INDIANA

Pesticide contamination in the St. Joseph River Watershed in Northeast Indiana has been a concern since atrazine was detected in the post-filtration water supply of the city of Fort Wayne in 1995. The St. Joseph River originates southern lower Michigan and provides drinking water for Fort Wayne's 200,000 citizens. In addition, the watershed has been shown to have a high capacity for surface-ground water exchange. In response to public and municipal concerns, the St. Joseph River Watershed Alliance, a public action coalition of private and public entities, has been monitoring pesticide levels in the drainage basin since early 1996.

Examination of the temporal distribution of the pesticide levels shows an increase by several orders of magnitude of the contaminant, since the inception of the sampling program. Highly localized contamination events associated with the "Spring-flush" phenomenon have introduced levels of atrazine and alachlor as high as 15 times the EPA's maximum contaminant levels. In addition, spring-flush contamination has increased in magnitude and localization since 1996. Geographic analysis using two-dimensional data analysis software reveals a northeastward migration of the contamination, away from the growing urban centers of Fort Wayne and Auburn, IN. When cross-referenced with land-use data, the geographic analysis shows an increase in contamination as the pesticide levels move to increasingly rural regions within the St. Joseph River watershed.