Algonquin Legends of Paw Paw Lake by Simon Pokagon

According to Grant Poole, current Water Quality Specialist for the Pokagon Band:

"The connection of the lake to the river is kind of still the same.  During flood condition the river would flow into the lake if not for some modern engineered structures and during lower water levels the lake drains to the river.  The landowners around the lake requested those structure to protect their homes.  

At the beginning of the book about Paw Paw Lake being a bay to Lake Michigan, there may have some truths to that as way back in time Lake Michigan was up higher or the dunes may have held water back to form a large lake in the Paw Paw River valley.  The Dowagiac River valley was once a large lake as well in geologic time.

The St Joseph River at one time flowed into the Kankakee River at South Bend then some glacier or geological event sent it north. Maybe when that happened the Paw Paw River lowered to expose todays Paw Paw Lake?"