I read they cut the power lines to allow copter access for repairs.
They no doubt have emergency generators to power lights and will have to get many more generators in place so the work can proceed day and night.
I don't know if they did or not, but the lines look intact on the video posted recently. They may have taken them out of service. I see 3 main transmission lines going out from the switchyard by the dam, basically due west. So they all go the same direction, probably to a main switching substation a couple of miles away would be my guess.