Over the last two years I have talked to staff of the city of Spokane and Spokane County in regard to the treatment plants.
I thought the wastewater should be pumped to the west or somewhere with holding areas that would use membranes to filter out the PCBs, etc. The holding areas would be allowed to dry and the residue swept out by some system. The water would go to reservoirs and wetlands, for restoring the aquifer or for irrigation.
To me it seems that getting every impurity out of the water is extremely expensive. Will we have years of drought? I do not think anyone knows, but as much preparation as possible needs to be taken.
The same goes for all treatment plants on the rivers.