Idaho’s Department of Water Resources and the Washington Department of Ecology have jointly announced an agreement that they say will “guide how the two states will continue to coordinate with each other about water supply issues in the face of unprecedented growth on top of the Rathdrum Prairie-Spokane Valley aquifer.” The aquifer is mostly in Idaho, but is the drinking water source for Spokane and the region, and it’s been the focus of lots of tension in recent years with growth on both sides of the border. Half a million people in both states depend on it for their drinking water.

The agreement calls for joint use of sophisticated computer modeling that can calculate the impacts of proposed withdrawals of water from the aquifer. “With this tool the
water managers can make well informed decisions about water use,” the two state departments said in a press release. A comprehensive bi-state study of the aquifer completed last year made this possible, they said.

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