The Mt. Paris Dam was built in the 1936 as the “Morning Star Dam” and connected to the Mt. Paris Mine. The mine closed in 1961, and as the dam had been mostly empty since 1970, it was officially decommissioned in 1985 and had holes blasted through the wall to allow the Cascade River to flow freely (one also assumes the name changed with its transfer of ownership).
It’s now a very nifty place to poke around and have a bit of an explore – though if you’re planning on doing the same, I’d recommend a handy supply of insect repellent to battle some particularly persistent march flies.