Negligible impact on the farming community. The reservoirs are well above the lower 4 dams. All that would be needed is to extend some pipe to the new water level. It may actually improve irrigation in that there will be less surface area to lose water to evaporation.

Other economic factors? Power isn't all that much even at full capacity. We'll likely see a new round of small modular reactors in the next decade. I think the first is slated for Idaho. Way less port traffic coming up the river after the Portland slow down driving Hanjin out.

There's lots I don't know, but there's a few things I think are correct.