SNY MAGILL WATERSHED MONITORING PROJECT: BASELINE DATA
Iowa Department of Natural Resources, Geological Survey Bureau,
Technical Information Series 32, 1994, p. 63-72

WATER QUALITY OF PRIVATE WATER SUPPLIES IN SNY MAGILL AND BLOODY RUN WATERSHEDS

L. S. Seigley(1) and G. R. Hallberg(2)

 

(1) Iowa Department of Natural Resources, Geological Survey Bureau
109 Trowbridge Hall
Iowa City, IA 52242-1319

(2) University of Iowa Hygienic Laboratory
University of Iowa; Oakdale Campus
Iowa City, IA 52242

ABSTRACT


Private wells in the Sny Magill and Bloody Run watersheds in Clayton County were sampled in October 1992 to determine baseline well-water and groundwater quality for these two watersheds. A total of 151 wells were sampled for total coliform bacteria, fecal coliform bacteria, and nitrate-nitrogen. Eighteen selected wells were also sampled for common herbicides. Well depths ranged from 34 feet to 570 feet (10.4 to 173.7 m) in depth; two springs were also sampled. Average well depth was 221 feet (67.4 m); 42% of the samples tested positive for total coliform bacteria; 10% tested positive for fecal coliform bacteria; and 40% contained >10 mg/L for nitrate-nitrogen. The mean nitrate-nitrogen concentration was 10.8 mg/L with concentrations ranging from <0.2 to 47.8 mg/L. Wells identified as being located in the Galena aquifer had the highest mean nitrate-N concentration (13.5 mg/L), the greatest percentage of wells unsafe for nitrate-N (54%), the greatest percent positive for total coliform bacteria (57%), and percent positive for fecal coliform bacteria (12%). Atrazine was detected in seven samples (39%) at concentrations ranging from 0.10-0.61 g/L; one sample detected deethylatrazine (an atrazine metabolite or breakdown product) at a concentration of 0.23 g/L.>