The dam was built in 1950 and designed with what was known at the time. Since then faults have been discovered and liquefaction has become much better understood. I do not think this is at all political.
I saw no new faults in the writeups I read, just some new soil borings about the base rock.
Prior to dam construction, it is an absolute certainty that numerous soil borings were made to establish the dam's foundation. That is how dams are properly designed.
So am unsure exactly how much 'new' data is being relied upon and instead just new engineering studies.
@PeteS in CA - do you know?
Also, this appears to be a dam built by a local governmental agency, so I wonder on what authority a federal agency can come in and over-rule the actions of a state and governmental agencies for something that appears wholly within the confines of California?