Info on Grand Lake St. Marys
Here is a quote from the following link to a web page. The canal system they are talking about is the Miami & Erie Canal. This page has a brief but direct history about Grand Lake St. Marys as well as the city of St. Marys. I bring this up because Grand Lake St. Marys currently is nothing less than a cesspool,(please Google it.) one which empties part of its overflow into the Maumee River Water Shed and eventually into Lake Erie. To the best of my knowledge both spillways are still functional.
"Grand Lake St. Marys is a part of the divide between the north and south waterways of the canal. Water flowing out of the canal to the east went eventually to Lake Erie and the other Great Lakes, while water flowing south and west found its way into streams and rivers (the Ohio River, for one) that are a part of the Mississippi River system."
http://www.stmarysdevelops.com/life-in-st-marys/history