Canal Overflow Weir

I've taken some photos of overflow weirs. But I don't have the time needed to try to find them. But I'll start these notes so that, if I come across a photo. it is easy to save it.

Canal Society of Indiana posted
For a canal to function properly, the engineers designed them to maintain a constant level of water of 4-5 feet depth. Normally the problem was getting enough water into the canal but like a modern bath tub you had to have a way for the excess water to be safely released. On the Wabash & Erie Canal at Defiance, Ohio a waste weir was built into the bank of the canal. Once the water level filled to the opening, excess could be safely directed into a nearby waterway.