If you're not gonna do numbers then I won't either. The main thing you need to keep in mind is that electric power has transport costs; sending electricity to a distant place means losing power along the way. Thanks, thermodynamics~ Therefore, if one wants to consume a lot of cheap hydroelectric power then they must build near the corresponding dam. Power at The Dalles campus is cheap, but that same power over in Portland is less cheap. By the time it can get across the Californian border it will have reached a price floor which is higher than the one in Oregon; Oregon electricity physically has a premium attached to it when Californians buy it. Note that this affects other high-wattage industries too; famously, aluminium smelters are generally built near dams.

The other thing to keep in mind is that datacenters generally pay market rates for everything. The datacenters in The Dalles, as well as e.g. Meta's installation in Prineville, pay the same prices for electricity and water as the residents. They do often get massive discounts on the land in the form of various tax boons. The Dalles has all three necessary resources for cheap (land, water, electricity) and also it's located in a high-desert biome which makes air conditioning extremely efficient.

See also the Stubsack thread, concomitant, on Awful, where we discuss water usage. Near The Dalles, I estimate that the local cherry farmers probably use more water than Google. Germane to California, the reason that the Colorado River is drying up is farmers abusing inherited water rights, not datacenters. You might also be interested previously, on Awful, where we consider how long it takes to build a datacenter.