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Yakima River Basin Groundwater Study

The final report of the 12-year USGS study on the impact of groundwater pumping on surface water in the Yakima Basin is now available:

View a copy of the report

Yakima River Basin Groundwater Study

October 2011 – Final USGS report on Yakima Basin groundwater

On Sept. 16, 2011, the U.S. Geological Survey released the long-awaited Yakima Basin groundwater study confirming groundwater connected to rivers and streams.

The first comprehensive groundwater flow model for the entire Yakima River Basin is detailed in the report. To view the report use the link in the right column .

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.

Results of the Yakima Basin USGS groundwater study and model will inform how we manage groundwater in the Yakima Basin. The model will provide the scientific platform for making decisions on a backlog of pending groundwater applications and for how mitigation may allow “new” water withdrawals.

History

In a 1999 MOA, Water Manager Partners: US Bureau of Reclamation and Yakama Nation agreed this model will be the accepted basis for making decisions and determining mitigation.

Ecology are working to engage its water partners, Reclamation, Yakama Nation, and watershed stakeholders in understanding the ramifications of the report.

While the conflict between groundwater and surface water isn’t new, we face new challenges to manage surface water and groundwater resources as a single resource, when historically we’ve managed them independently.

News release

Yakima Basin groundwater connected to rivers and streams - USGS News Release September 16, 2011

The report

‘Numerical Simulation of Groundwater Flow for the Yakima Basin’ by D.M. Ely, M.P. Bachmann and J.J. Vaccaro is U.S. Geological Survey Scientific Investigations Report 2011-5155.

Study done in three phases

The groundwater study in the Yakima Basin was done in three phases:

The first phase included (1) project planning and coordination, (2) compiling, documenting, and assessing available data, and (3) initial data collection.
The second phase consisted of data collection to support (1) mapping of hydrogeologic units, (2) estimates of groundwater pumpage, (3) estimates of groundwater recharge, (4) assessments of groundwater-surface water interchanges, and (5) construction of maps of groundwater levels. Together, these five elements provided the information needed to describe the groundwater flow system, the conceptual model, and provide the building blocks for the hydrogeologic framework.
In the third phase, six structural basin models and one regional model of the groundwater flow system was constructed in order to integrate the available information. The numerical models were used to gain a further understanding of the flow system and its relation to surface water, and to test management strategies. The models were developed and will be maintained in such a fashion that they will be available and open to others. The models provide a state-of-the-art technical tool to help water managers make sound decisions in the Basin, where water shortages are a chronic problem.

Additional information

Yakima River Basin Groundwater Study Background - information leading up to the release of the final report
Yakima Basin Current Activities
Location of the Yakima River Basin and vicinity
Yakima River Basin - Link to the USGS Yakima River Basin web page
Yakima Basin Integrated Water Resources Management Plan - Office of Columbia River

Contact

Tom Tebb
Department of Ecology, Central Regional Office
(509) 574-3989
gteb461@ecy.wa.gov