A little more information on the Hyatt Powerplant refurbishment operation.....
The article is from 2009, but describes some of the ongoing work that was done in the 2000-2010 decade to refurbish some of the generator units at the Hyatt plant. I doubt that it relates to today’s situation - that is, I’m certain that they haven’t had unit 6 out for that many years. Although, budgets being what they are in government, they may not have started the unit 6 work until recently. (as a side note, the Chickamauga Dam lock replacement project in Chattanooga has been sitting in an idle, half-competed condition since George W. Bush left office).
Here, also for your viewing pleasure, is a slideshow presentation on the work done on units 2 and 4, with an implied project to continue on to unit 6. This is dated 2006...
http://www.slideserve.com/foster/project-status-update-hyatt-modernization-program
And one more link on the power plant, this one from the California DWR, with some nice pictures. There seem to be some discrepancy on the megawatt/MVA capacity of the 6 units depending on what source you read. I don’t know why.
This may have been linked to earlier in the thread.
https://mavensnotebook.com/wp-content/uploads/2017/02/Hyatt-Powerplant-Oroville-Dam.pdf
Fascinating stuff. The turbine work alone is amazing. 95+% efficiency is very good for a vertical system.