Doing reading, bass will use old nests and new nests. Old nests, because the nest itself is rock, will last quite a while. Rather, the nesting sites will be covered with debris and silt if the water is running and prime to incoming debris from the forest. They will use their nest from prior years, or other basses nests if they can rather than make another. Smallmouth/bluegill/sunfish can move "boulders" of a maximum of 255mm, or 10 inches. Turtles aren't common here, usually down by the ocean, and the only snakes are single species of garden snake, and the very rare and elusive rubber boa, both don't like to swim, nor dive. PNW side of the cascades is blocked from most North Americas smaller creatures that cannot traverse the passes. No poisonous snakes or spiders that aren't hitchhikers.
Additionally I am reading that bass tend to nest alone. Bluegill tend to create large nesting sites. Also bass like to make their nests around shelter, or natural dips in the terrain. They also tend to be lazy about their nests and often just clear an area out.
Considering we don't get much high winds in the alpines here, and more just rain, it's likely these can last years and these are from either an existing or past population of bluegill or actual sunfish wish due massive breeding sites.
See large mouth bass nests (couldn't even find nests with multiple pairs that wasn't actually bluegill pictured)