Over 200 ground water wells in northern lower Michigan were sampled from nine land use classes and several geologic strata during 1974 and 1975 for concentrations of NO3-N, NH4-N, PO4-P, Cl, Fe, Ca, Mg, K, and Na. Mean well depth was 38 +- 24 m, with 92% of the wells having depths of from 15 to 90 m. In general, the quality of ground water for the ions tested was within U.S. Public Health standards. Multiple comparison tests among land use classes for NO3-N were significant (P < 0.05) and in every case agricultural related land use classes had concentrations above the regional mean of 0.72 +- 0.04 g/m3 (mg/l) NO3-N. The importance of both anthropogenic and natural Na inputs into ground water was noted for the region. The patters of ion concentration for PO4-P, K, Mg, and Ca showed only a few differences among land classes; while Cl and Fe concentrations had no discernable pattern. No significant differences in NH4-N ground water concentration between immature agricultural ecosystems and mature forest systems were found.