RECHARGE OF THE SNAKE RWER PLAIN AQUIFER: TRANSITIONING FROM INCIDENTAL TO MANAGED1

Authors

  • Gary S. Johnson,

  • Walter H. Sullivan,

  • Donna M. Cosgrove,

  • Robert D. Schmidt

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      Respectively, Assistant Professor of Geology and Geologic Engineering, University of Idaho, 1776 Science Center Drive, Idaho Falls, Idaho 83402; Manager, Sample Mgmt. and Risk Technologies Dept., Lockheed Martin Idaho Technologies Co., P.O. Box 1625, MS 3960, Idaho Falls, Idaho 83415–3960; Research Associate, Idaho Water Resources Research Institute, University of Idaho, 1776 Science Center Drive, Idaho Falls, Idaho 83402; and Research Hydrologist, U.S. Bureau of Reclamation, 3396 285th Avenue N.E., Isanti, Minnesota 55040 (E-Mail/Johnson: johnson@if.uidaho.edu).


  • 1

    PaperNo. 98010 of the Journal of the American Water Resources Association.Discussions are open until October 1,1999.

Abstract

ABSTRACT: Declining ground-water levels and spring discharges have heightened water user concerns about the sustainability of the Snake River Plain aquifer in southern Idaho. Diminished recharge from surface water irrigation and increased irrigation pumping have been depleting the aquifer at a rate of about 350,000 acre-feet/year. Previously, aquifer conditions were treated as an uncontrollable consequence of weather and development activities. With increasing competition for available water, the State appears to be progressing through a three-stage process of recharge management. The first stage is that which has occurred historically, where recharge is largely an incidental effect of surface water irrigation. The second stage is the implementation of intentional recharge with little regard to identifying or maximizing benefits. Idaho has been at this stage for the past few years. The State is entering a third stage in which recharge sites will be located and designed to meet specific water user and environmental objectives. Preliminary estimates using numerical and analytical models demonstrate that managed recharge within a few miles of the river will result in short-term increases in spring discharge. More distant recharge sites are needed to provide longer-term benefits. The primary challenge facing implementation of the managed recharge program will be the balancing of economic and environmental costs and benefits and to whom they accrue.

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