News Release

U.S. Department of the Interior
U.S. Geological Survey

Release: September 16, 2011

Contact:
Matt Ely
253-552-1622

John Clemens
253-552-1635

Yakima Basin groundwater connected to rivers and streams

[Editors: The USGS project page is http://wa.water.usgs.gov/projects/yakimagw/ .]

TACOMA, Wash. — The first comprehensive groundwater flow model for the entire Yakima River Basin is detailed in a report released today by the U.S. Geological Survey.

The new computer model simulates the groundwater system and its interaction with rivers and streams, and integrates information produced by the USGS over the last 12 years of assessing the Yakima River Basin groundwater resource, in cooperation with the Bureau of Reclamation, the Washington State Department of Ecology, and the Yakama Nation.

Because of increasing demand for water in the basin, managers need an integrated understanding of the aquifer system and how it is connected to rivers and streams. USGS scientists have studied the aquifer system's water levels, hydrogeology, pumpage, recharge, flow, and connections to surface water--all of which are incorporated in the model. Some of this information was released in a series of earlier reports, and this thirteenth report in the series documents the model and the various scenarios simulated by the model.

In one scenario, the model was used to simulate the historic (1960-2001) interaction between groundwater and surface water. Simulation results indicate that groundwater pumpage in the basin reduces streamflow by about 194 cubic feet per second; the effects of domestic well pumpage on streamflow are small, generally ranging from 8 to 10 cubic feet per second.

The report, "Numerical Simulation of Groundwater Flow for the Yakima River Basin Aquifer System, Washington," by D.M. Ely, M.P. Bachmann, and J.J. Vaccaro, is published as U.S. Geological Survey Scientific Investigations Report 2011-5155 and is available on the Web at http://pubs.usgs.gov/sir/2011/5155 .

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