The following sections review various water leasing programs throughout the western United States to provide a comparison with the 2001 Dungeness water-leasing program. The review is limited to formalized water leasing programs operated by federal, state, and nonprofit organizations. The review provides an overview of individual programs, identifies key characteristics, and summarizes participation and lease rates for multiple years with a particular focus on 2001 and 2002. Throughout the western United States, water acquisitions for non-consumptive uses such as environmental mitigation and flow augmentation are increasing. Commonly used acquisition methods include permanent purchases, leases, and donation. With the exception of Wyoming, environmental water sales have occurred in every western state. This market sector has increased steadily since 1990 when less than $500,000 was spent on water purchases. In comparison, more than $11 million dollars were expended from 1990 to 1997 on purchases of water to improve habitat conditions for fish and wildlife. Expenditures for environmental water acquisitions throughout the western United States are currently estimated at $20 million per year. The Pacific Northwest has one of the most active markets within the western United States.4 This is largely due to federal efforts to increase stream flows for federally protected species. From 1990 to 1997, approximately 94 percent of all environmental water acquisitions occurred in the Pacific Northwest. Market activity within the region is continuing to increase. In addition, from 1998 to 2001, a total of $11.9 million was spent to acquire approximately 1.09 million acre-feet of water for flow enhancement.5 Within the Pacific Northwest, active water leasing programs have been developing in the Yakima and Salmon Creek basins of Washington, the Walla Walla, Klamath, and Deschutes basins in Oregon, the Snake and Lemhi basins in Idaho, the Bay-Delta region of California, and the throughout various basins in Montana. The following section provides a review of these water-leasing programs.