Introduction

The Spokane Valley-Rathdrum Prairie (SVRP) aquifer supplies water to over 400,000 residents in Spokane County, Washington, and Kootenai County, Idaho. The area includes the rapidly growing cities of Spokane, Washington and Coeur d'Alene and Post Falls, Idaho. The aquifer consists of thick deposits of coarse sediment, and was designated a "Sole Source Aquifer" by the Environmental Protection Agency in 1978 in response to local concerns about aquifer vulnerability to water quality degradation. Urban growth and increasing ground-water withdrawals and surface- water appropriations have raised concerns about water availability in the SVRP aquifer and declining streamflows in the Spokane and Little Spokane Rivers which may periodically receive water from the aquifer.

Water management of the SVRP aquifer occurs at federal, state, and local levels. The states of Washington and Idaho have primary responsibility for water allocation and water quality, however, local governments are increasingly being called upon to consider water supply and quality implications in land use planning. The potential influence of the SVRP aquifer on surface- water flows and quality further complicate aquifer management.

In order to deal with these issues, regional chambers of commerce and others prepared appropriations requests for Congress, which were granted in part in late 2003, with the appropriation of $500,000 to the U.S. Geological Survey (USGS) in consultation with the states of Washington and Idaho to accomplish the project to provide the tools that the states needed to address the hydrologic issues at hand for management purposes.