Centers for Disease Control and Prevention, Dept. of Health & Human Services
Abstract
"Domestic wells, cisterns, or springs supply drinking water to eighteen percent of the households in the nine upper midwestern states. Many of these wells were in areas of the Missouri and Mississippi River basins that were flooded during the 1993 midwest flood. After the flood waters receded, many state and county sanitarians reported that water samples collected from domestic wells in the flooded river basins contained coliform bacteria. Since the nature and magnitude of this contamination was unknown, a survey was initiated to assess the presence of bacteria and chemicals in water drawn from domestic wells in the states that were severely affected by the flood. The survey was conducted in May to November of 1994 by state health and environmental departments of nine midwestern states with assistance from the Centers for Disease Control and Prevention (CDC). Because samples were collected one year after flooding and few of the sampled wells had preflood water quality results, the effect of this disturbance on the water quality of domestic wells could not be evaluated. Water samples were collected from 5520 households with domestic wells. These houses were near the intersections of a 10 mile grid overlaid on a map of Illinois, Iowa, Kansas, Minnesota, Missouri, Nebraska, North Dakota, South Dakota, and Wisconsin. Samples were usually collected from the household faucet that was used to supply drinking water. Coliform bacteria, Escherichia coli, nitrate, and atrazine were measured. The coliform bacteria and E. coli serve as indicators of contamination and their presence in water supply systems indicate an increased risk for diarrheal illnesses. Fertilizers and herbicides are intensely applied in rural areas of the Midwest, the location of most domestic wells. "[Centers for Disease Control and Prevention, National Center for Environmental Health]."NCEH 97-0265."The 1994 Midwest Well Water Survey was funded by United States Public Health Service Office of Emergency Preparedness through the 1993 Midwest Flood Supplemental Appropriations
