The Yakima River flows 215 miles from the outlet of Keechelus Lake in the central Washington Cascades southeasterly to the Columbia River, draining an area of 6,155 square miles. The Yakima River Basin is one of the most intensively irrigated areas in the United States. Population in the Yakima River Basin was about 238,000 in 1990.
Increasing demands for water for municipal, fisheries, agricultural, industrial, and recreational uses will affect the ground-water resources of the basin. A better understanding of the ground-water flow system and its relation to rivers and streams is needed to effectively manage the basin's water resources.
In cooperation with the U.S. Bureau of Reclamation, the Washington Department of Ecology, and the Yakama Indian Nation, the USGS is studying the ground-water system in the Yakima River Basin and how it interacts with rivers and streams in the basin. The study includes data collection, mapping of hydrogeologic units and ground-water levels, and a computer numerical model to bring together all the information.