As part of their state-issued NPDES (National Pollutant Discharge Elimination System) Permit, the Spokane County Regional Water Reclamation Facility (SCRWRF) will be conducting a required mixing zone study of the Spokane River.
The study involves a dye tracer test where Rhodamine WT, an environmentally safe red dye, will be added to the facility’s effluent water before it enters the river. The dye will allow water specialists to analyze how the effluent from the facility mixes into the river as well as interactions between the aquifer and the river in this area. Water from the Spokane Valley-Rathdrum Prairie Aquifer enters the river in this section, and the volume and flowrate of the water entering can be estimated with the dye tracer test.
The test is scheduled for Tuesday, August 5, 2025, from 11:00 a.m. until 3:00 p.m. Those conducting the test will use a boat to access different locations and depths of the river to gather data on dye concentrations. A drone will also be used to capture aerial views of the dye mixing.
The effluent enters the Spokane River just east of Spokane Community College. The dye will be best viewed at the intersection of N Havana St and E Upriver Dr, but it will be visible for up to a half-mile downstream for the duration of the testing timeframe.
For more information, go to the Spokane County Regional Water Reclamation Facility page at www.spokanecounty.org.