Abstract.LGWRES is a simplistic program, for the HP‐41C series of programmable calculators, to determine the lifetime of ground‐water reserves in years; total use over the lifetime of the reserves; precentage of domestic and agricultural uses; additional years of possible agricultural use realized by dedicating the domestic use to agriculture; and percentages of total use, domestic use, and agricultural use that could be sustained by annual replenishment to the ground‐water reserves, within the “safe yield