Niagara Falls Does Not Move Backward: Water Flows One Way from Lake Erie to Lake Ontario

Niagara Falls does not move backward. The falls are the outlet of the Upper Great Lakes system: water flows from Lake Erie, through the Niagara River, over the falls (Horseshoe, American, Bridal Veil), into the Lower Niagara River, and onward to Lake Ontario. The flow is unidirectional, driven by gravity and the elevation drop (~99 m / 325 ft total). The falls do retreat upstream over geological time due to erosion of the underlying shale and limestone caprock, but the water itself never flows backward.