The Impact of Agriculture on the Waters of the Idaho Portion of the Snake River Basin, USA

The Impact of Agriculture on the Waters of the Idaho Portion of the Snake River Basin, USA

Robert L. Mahler

Department of Soil and Water Systems, University of Idaho, USA

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The Snake River Basin is the largest sub-basin of the International (Canada and USA) Columbia River Basin in North America and covers 280,000 km2. Over 70% of the Snake River Basin is within Idaho. The Snake River is 1,674 km in length and the majority of the Basin is dry with annual precipitation averaging less than 300 mm. The snowpack in the mountains of the northern part of the Basin provide significant surface and groundwater resources for the Idaho portion of the Snake River Basin. Conse- quently, surface water and groundwater withdrawals exceed 64,000,000,000 l/day. Over 86% of the withdrawn water is currently used on 1,500,000 ha of irrigated agricultural land. The purpose of this paper is threefold: (1) to understand current and future pressure on the limited water resources of the Snake River Basin, (2) to gain an understanding of the value of the public places on the water resource and agriculture, and (3) to suggest sustainable practices that can be used in the future to support population growth, wise water resource use, and agriculture in the Snake River Basin. Currently, the basin does not have excess water, so water-use distribution must change as the population grows. Currently, the human population within the basin is increasing at the rate of 25,000 to 30,000 people per year. A significant portion of this growth has caused the conversion of irrigated farmland to cities. Thus, irrigated agriculture’s share of water will decline from 86% today to less than 72% by 2040. Mail- based surveys were used to understand how the public view the Snake River Basin’s water resource. The majority of Snake River Basin residents are supportive of agriculture’s use of water (84%) and consider irrigated agriculture an important cultural aspect of Idaho (77%). The following four strategies should be the focus of a long-term sustainable plan: (1) use land-use planning to determine which agricultural land should be protected from urban development, (2) improve water use and irrigation efficiency in irrigated agriculture, (3) reduce the amount of irrigated land devoted to low value crops, and (4) provide consumer education about the agriculture – water resource – population nexus in the Snake River Basin of Idaho.


Public concerns, Water issues, Public opinion, Water quality, Water quantity


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