Community based risk assessment of exposure to waterborne contaminants on the Crow Reservation, Montana

Margaret Joy Slack Eggers
Microbiology, Montana State University
July, 2014


The goal of this collaborative research project undertaken by the Crow Reservation community, Little Big Horn College and Montana State University Bozeman has been to improve the health of Crow community members by assessing, communicating and mitigating the risks from local waterborne contaminants. The Reservation's surface waters have always been greatly respected by the Crow people, valued as a source of life and health and relied upon for drinking water. About fifty years ago, rural families switched to home well water instead of hauling water from the rivers. Many families went from having an unlimited supply of free, good quality river water, to unpalatable well water dependent upon an expensive-to-maintain plumbing system. Tribal members questioned the health of the rivers and well water due to visible water quality deterioration and potential connections to illnesses and initiated this research project. We share what we have learned as tribal members and researchers about conducting community-based risk assessment and using our data to improve Tribal and river health. Initial research on river water quality revealed significant microbial contamination. Collaborations with several microbiologists revealed substantial E. coli and Cryptosporidium river contamination as well as Helicobacter pylori in home water supplies. We found that about 55% of home wells are unsafe to drink due to either mineral and/or microbial contamination. Depending on the river valley, 11% to 58% of home wells exceed the cumulative risk level of concern for mineral contaminants. Exposure to contaminated well water exacerbates the community's existing health disparities due to the confluence of the area's geology, extensive agriculture, lack of public environmental health education, jurisdictional complexities of reservations, already vulnerable health status and families' limited financial resources for mitigating poor quality well water. Limited resources as well as the links among ecosystems, cultural practices and public health will increase the already existing impacts of climate change on reservation communities. Flood frequency, late summer water shortage and fire severity are increasing while water quality is declining. Risk communication and risk mitigation, not just risk assessment, have been and continue to be central to our project and pursued through numerous venues and collaborations.