Just a few quick notes on the power line situation. The following image was taken prior to the event. This is the original transmission line configuration...
In the original configuration, there are 3 ea. 230 kilovolt transmission circuits that tie to the plant's switchyard and a transmission switching substation roughly west of the plant. 2 circuits are on the lower (downhill, closest to the erosion) tower and 1 on the upper tower. Typically, lines of this voltage are capable of carrying 500-800 Megawatts of power. The plant is rated, with all 6 units on line at full output, at 819 MW. Basically, the station is designed to have 3 circuits to allow for contingency loss of one, or for removing one line from service for maintenance.
Recently, they re-arranged the conductors and removed both circuits from the lower tower in preparation for the possibility that it could be lost to erosion from further damage and use of the main spillway. This resulted in only 2 instead of 3 circuits connecting the plant's generation to the power grid, both of which are located on the upper transmission tower.
What they're doing now is installing "temporary" wood poles to allow the relocation of one or two circuits farther up the hill to less risky ground. I use quotations on "temporary" because in the power industry, things like this tend to stay in service for decades. What this will allow is to have the full complement of 3 circuits tying the plant to the grid (which will come in handy when they finish maintenance on the 6th generating unit), and will take one or two circuits well out of harm's way if the main spillway experiences more damage or erosion.
They are also removing the lowest tower, and it appears that they're digging up the footers as well, so a tower is not likely to occupy this spot again. Image from ER333's post above...
