The Washington-Idaho state boundary is a political boundary
that cuts across the Spokane Valley-Rathdrum Prairie (SVRP)
aquifer, and across which the Spokane River flows. The area
contributing drainage to the Spokane River stretches from
WRIA 57 clear across Idaho to the Idaho-Montana state boundary.
Activities within this catchment area affect flows of the Spokane
River through WRIA 57. Such influences include snow pack accumulation
and melt in the Rocky Mountains, operation of the Coeur d'Alene
Lake reservoir, and the use of groundwater resources in the
Rathdrum Prairie aquifer.
On-going efforts that may affect the interstate management
of water resources of the Spokane River system and groundwater
aquifers include applications
for water rights, the findings of the USGS
interstate aquifer study, and relicensing of the Avista
Utilities' Spokane River Project.