Investigations in townships surrounding the Grand Traverse Bay of Michigan show identifiable geographic relationship between ground water quality and land use. Wells averaging 32 m deep in thinly populated areas (cherry orchards) measured an average of 3.75 ppm nitrate‐N, indicating the effect of prolonged years of fertilizer application. Wells averaging 19 m deep in predominantly residential areas had an average of 1.31 ppm nitrate‐N, indicating possible contamination from septic tank effluents. An average of 0.18 ppm of ammonia‐N was detected in marshy wetlands. An analysis of temporal variations in ground water quality with reference to precipitation, streamflow, and a trend component provided high as well as low R2 (0.92 to 0.12; R2 = square of the multiple correlation coefficient) producing regression models, indicating the effect of site specific conditions. A year‐long observation of a sample well (43 m deep) surrounded by cherry orchards had an average of 18.25 ppm nitrate‐N in a range of 13.09 to 20.64 ppm, almost double the standard considered safe for human consumption. Ammonia‐N and chloride measurements from a shallow well (12.5 m deep), surrounded by residential and commercial activities, showed synchronized variations over a year (correlation coefficient r = 0.75, significant at 1% level), suggesting the existence of a common source of contamination. In summary, it is reiterated that the analysis of ground water quality problems require a different philosophical approach from those of water quantity and surface water quality modeling.
No takes yet. Share an insight, caveat, or question.
R. Rajagopal (1978) studied this question.