The Spokane Valley-Rathdrum Prairie aquifer is designated a "sole source aquifer" and extends across an area covering about 325 square miles and provides drinking water for nearly 400,000 people. Originating from the southern end of Lake Pend Oreille, the unconfined aquifer extends beneath the Rathdrum Prairie in Idaho, and Washington's Spokane Valley. Most of the groundwater then flows north up the "Hillyard trough", and discharges as springs along the Little Spokane River. The view above includes all of the land area over the aquifer (primarily in the low-lying valley bottoms, as well as the area surrounding the main body of the aquifer, that is, the contributing adjacent watersheds. The aquifer boundary is indicated by the dotted white line; Spokane County's Aquifer Sensitive Area (ASA) is indicated by the orange line. This view clearly shows that most of the people in the Spokane area, and in North Idaho, live directly over, or adjacent to, the aquifer.
Start the tour:
Click on the numbered stops on the map above [to
be added later], or in the index below, to start the tour.
It is suggested that you visit the field trip stops in order, that is,
visit the stops in sequence for your best overall understanding of the
aquifer system (from upstream to downstream). Each stop on the tour
takes you to another web page that describes the highlighted feature (and
it may include a photo too). Have fun!
For more information about the aquifer system you can contact the Spokane
County Water Quality Management Program office, or the Idaho Division
of Environmental Quality.