Investigation of coliform contamination in private well water on the Crow Reservation

The Crow reservation has a rural population that depends on home well water for municipal use and home wells have bacterial contamination that are constructed at various depths or wells that do not have a suitable well cap. This research will examine different correlations between presence/absence of coliform and physical characteristics along with well protection factors. Also, examine the spatial distribution of coliform contamination. Physical characteristics include alluvium type, land cover type and distance to river. Well protection factors include well cap type, well depth, livestock presence and well age. One hundred samples were collected throughout the Little Big Horn Valley at home wells. Sample analysis was conducted using the Colilert IDEXX Quanti-Tray 2000 method. Spatial data was acquired through well logs, 2011 National Land Cover Dataset, the USGS National Elevation Dataset and ArcMap. The samples will be analyzed using logistic regression to identify odds of coliform contamination based on physical characteristics and well protection factors. Preliminary results indicate there is a relationship between coliform contamination and wells that are in alluvium and in shallow wells. The government of the Crow tribe can decide how to use the results for mitigation efforts and awareness for homeowners with contaminated wells.