Isotopic and chemical characterization of ground waters in the vicinity of Flagstaff, Arizona

Abstract

The sustained yield of a well field adjacent to Lower Lake Mary reservoir, south of Flagstaff, Arizona, has been calculated in two separate studies, and the results differ significantly. One reason for the difference is the lack of understanding of the effect that the reservoir has on recharge to the well field. Samples were taken from various surface waters, springs, and production wells in the area surrounding Flagstaff to chemically characterize the waters and to examine the potential recharge source(s) to the Lake Mary well field. Results indicate that nearly all ground waters in the area are calcium-magnesium-bicarbonate in composition, but they differ significantly in total hardness. Isotopic values of the samples indicate that only one well within the Lake Mary well field is definitely receiving significant recharge from the reservoir.