Wanapum Dam was built in 1959 and is more than a mile long.
Sounds like your near the Tri Cities. If their lowering 20 feet that’s going raise the pool behind McNary quite a bit. And Pasco has been trying to the corp of engineers to lower all the levies for years!
For those out there, this dam was built and owned by Grant County PUD and loosing it would kill Grant County as that’s where Microsoft, Google and a bunch of others built their data storage centers because of the cheap power from the dam.