Groundwater Model to Aid Bi-State Water Protocols

The Idaho Department of Water Resources and the Washington Department of Ecology have put the finishing touches on an agreement that will guide how the two states will continue to coordinate on water supply issues in the face of unprecedented growth on top of the Rathdrum Prairie-Spokane Valley aquifer.

The agencies' water resources programs administer water rights and make determinations about water availability in their respective states. The aquifer serves more than 500,000 residents in portions of Spokane County, Washington and Bonner and Kootenai counties in Idaho.

The agreement details continued coordination involving maintenance and improvement of the technical tools developed in a bi-state water study. The comprehensive Idaho-Washington-U.S. Geological Survey study of the aquifer, which was completed last year, resulted in a numerical computer model that represents the best current knowledge of the groundwater flow system and how the aquifer interacts with the Spokane River in both states.

The computer model allows water managers to enter data about a proposed withdrawal and see just how it would affect water levels in the vicinity of the withdrawal.

The new memorandum of agreement establishes a collaborative “modeling committee” of experts from both states to manage and secure the computer model and make sure both parties agree to any updates. The committee will decide what enhancements to the model would be valuable and establish the direction of research to enhance the model.
The agreement was signed by IDWR Director David Tuthill, and Ecology Director Jay Manning.

The committee will establish protocols to make sure that the most recent version of the model is available to local government and the general public.