If I am not mistaken, the reason those data centers are close to the dams/et. al., is because it is a lot cheaper for them to get the power a short distance away from where the power is generated. That plus the solar and wind power potential is much better there than on this side of the Cascades. I think they can also tap into the river for cooling?In all honesty the NW transmission "grid" is in moderate shape and always expanding and improving but the expansion of the grid is incredibly expensive and time consuming. One of the things sucking up tremendous amounts of power and the cause of expansion are data centers. BPA has a tremendous amount of work scheduled in the next 10 years to the tune of 3 billion+ dollars just for the company I work for. That total is not inclusive of all the other work planned by BPA for other contractors.
I know my neighbor spends a lot of time working on projects for power generation upgrades at the dams.