Lake Franklin Pierce in New Hampshire is a recent lake, in 1926 it was created and has a hydro electric plant at the North and South end. The pipes were going to be replaced, and were half finished when work stopped. I’m guessing the money ran out. So the pipes still leak and in the winter the leaks freeze in interesting forms.
The pipes are very similar to barrels that hold water on top of buildings in NY.
- How to thaw a frozen pipe this winter (confused.com)
- Barn Raisings and Leaky Faucets (patcegan.wordpress.com)