I live by Shenango in Mercer Co. Moraine is like 30 mins south.

We have our lake fed through a dam. It is man made. Big one. Ski boats and a marina and all that. They lower it in late fall, several feet.

Anyway, from what Ive gathered over the years, it does protect shorelines and so forth--but it prevents flooding from snow melt when it warms up in spring. I think this is the primary reason. Someone correct me if Im wrong.