nated aquifer will be reflected in the potential gains or value of improvements to the ground water resource and will be site-specific.

The empirical findings of this Woburn, Massachusetts, case study refute conventional wisdom concerning the economic efficiency of ground water remediation at Superfund sites for the sole purpose of restoring drinking water supplies (i.e., that the costs of remediation far outweigh the benefits). In some cases ground water remediation can be the efficient alternative; it should not be dismissed without conducting a cost-benefit analysis. This case study also highlights the complexities involved in conducting an empirical analysis of the value of restoring ground water resources and the impacts of uncertainties in the economic and physical dimensions, and in potential health consequences, and the public response to ground water usage.

The final case study concerns the potential application of the valuation framework described in Chapter 3 and some valuation methods described in Chapter 4. Options in this Tucson, Arizona, case include ground water recharge using Central Arizona Project (CAP) water or treatment of CAP water prior to usage. This study provides information on the types of methods that could be used to value a complete suite of ground water services for both options.

CHALLENGES IN WATER QUALITY MANAGEMENT Treasure Valley, Oregon

Background

The Treasure Valley of eastern Oregon and southwestern Idaho is high desert (10 inches of precipitation on average per year) that is intensively irrigated using surface water from the Owyhee, Malheur, and Snake Rivers. All the water of the Owyhee and Malheur Rivers (tributaries of the Snake River) is diverted to irrigation. Stream flow below the diversions is maintained by irrigation return flows and recharge from a shallow aquifer supported in part by irrigation recharge (Gannett, 1990).

Crop agriculture in the area is characterized by a range of high valued crops including potatoes, sugar beets, and onions, as well as cereal grains and hay. In the Oregon portion of the valley, approximately 180,000 acres are in irrigated crop production (Schneider, 1992). The primary source of water irrigation is from federal (U.S. Bureau of Reclamation) reservoirs and distribution systems. In terms of total agricultural sales, animal agriculture (cattle and dairy) accounts for 36 percent of sales, onions 25 percent, potatoes 11 percent, sugar beets 9 percent, cereal grains 9 percent, and the remaining crops 10 percent.

Ground water is used largely for industrial or human consumption. Between 1983 and 1986, the Oregon Department of Environmental Quality (ODEQ) tested water wells in the study area. Elevated nitrate levels were found in 67 percent of the wells tested; 35 percent of the wells exceeded the federal drinking water



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