USING STORED GROUND WATER WITHOUT DEPLETING A FULLY APPROPRIATED STREAM

摘要

If a stream's flow is already committed, connected ground water is beyond use unless surface-water rights are retired, or the river is physically isolated from the aquifer. Both may be infeasible. An alternative conjunctive-use strategy would "store" future streamflow in the form of invested money. Some 460,000,000 acre-feet are stored in the valley-fill of the Rio Grande near Albuquerque, NM, but the river's flow is fully committed. Depletion of streamflow would increase by 84,700 acre-feet per year at the end of 100 years if an additional 100,000 acre-feet per year were pumped. In municipal use with 50-percent return flow, and with an ever-increasing part of the production sent directly to the river, 77,700 acre-feet per year at 40 years, diminishing at 100 years to 30,600 acre-feet per year, could be delivered for use while preserving the river's flow. A price of $1.22 or less per 1,000 gallons (for the first 100 years) would establish a fund to maintain perpetual direct pumping to the river to offset depletion, even after no water at all is available for use.