NITRATE CONTAMINATION IN OREGON WELL WATER : GEOLOGIC VARIABILITY AND THE PUBLIC ’ S PERCEPTION 1 Aaron C . Kite - Powell and Anna

Approximately 4.5 million people in the United States who rely on well water are exposed to nitrate-N concentrations exceeding the 10 mg/l standard. In this study in the Southern Willamette Valley in Oregon we reassessed nitrate-N in rural wells sampled in 2000-2001, compared nitrate-N concentrations among geological units, and surveyed residents about their perceptions of well water quality. Nitrate-N concentrations were again sampled in 2002 and found to have increased significantly from the previous period. With rapid population growth in the area, the potential health risk in drinking well water that exceeds 10 mg/l nitrate-N warrants continued public education. Nitrate-N concentrations were found to be higher in the Holocene alluvium of the Willamette River and the Pleistocene sand and gravel post-Missoula Flood deposits. Researchers conducting future studies may choose to stratify and monitor wells by geologic unit and by other parameters that estimate input of nutrients to the environment. Opinions differed between agricultural landowners and nonagricultural landowners with regard to the impact that agricultural fertilizers may have on water quality. Participants were supportive of a range of regulatory actions that might be used by homeowners or landowners to address ground water contamination. Given that the area is now designated a Groundwater Management Area, understanding local stakeholders’ perceptions is critical and strategic and has the potential to help public agencies manage potential conflicts of opinion among stakeholders, build consensus, and help guide the approach to restoring ground water quality. (KEY TERMS: drinking water; geospatial analysis; ground water management; nitrate; public perception survey; water quality; wells) Kite-Powell, Aaron C. and Anna K. Harding, 2006. Nitrate Contamination in Oregon Well Water: Geologic Variability and the Public’s Perception. Journal of the American Water Resources Association (JAWRA) 42(4):975-987.