Optimizing Salvageable Water Resources in a Semi-Arid Inland Basin

Abstract

The purpose of this investigation was to characterize salvageable water resources in the semi-arid Tucson basin and to evaluate appropriate treatment and control methods and management procedures for reuse of these salvageable waters. A preliminary inventory of salvageable water resources in the Tucson basin indicated a conservatively estimated annual total of 30,000 acre-feet available, as follows: municipal system effluents, 25,000 acre-feet; industrial cooling effluents, 1,000 acre-feet; urban runoff, 2,000 acre-feet; and industrial processing waters and other minor sources, 2,000 acre-feet per year. The City water utility has ample information on hand regarding quality of municipal effluents; data collected during this study are sufficient to define representative quality of industrial effluents; and presently developed processes evidently are adequate for the control and treatment of salvageable waters. However, little was known of the quality of urban runoff in this semi-arid environment, and efforts were directed toward exploratory sampling and analysis as indicators of potential problem areas in runoff quality. A ground-water recharge investigation at the Rillito Creek recharge site near Tucson produced a mathematical model which can be used to represent fluctuations of ground-water levels resulting from line-source recharge. Findings can be applied to alternative management schemes in the utilization or storage of salvaged waters. Initial formulation of management alternatives by examination of local salvaged-water subsystems appeared not to require elegant mathematical solution but rather an improved system framework defining community objectives and criteria for salvaged water allocation.