Which of the Great Lakes lies above and feeds into Niagara Falls?

The Great Lakes form a vast, interconnected freshwater system, with water flowing generally from west to east due to changes in elevation. Water from the upper lakes—Superior, Michigan, and Huron—all drains into the fourth lake in the chain. This body of water acts as the upper basin for the Niagara River. As the river flows north, it encounters the Niagara Escarpment, a massive cliff that separates this lake's higher elevation from the much lower basin of Lake Ontario. It is this dramatic descent that creates the world-famous Niagara Falls.

The lake positioned directly above this massive drop is therefore the one that feeds it. While it is the fourth-largest of the Great Lakes by surface area, it is the shallowest and holds the smallest volume of water. Despite this, all of its outflow, carrying the water from three other lakes with it, is channeled into the short but powerful Niagara River. An incredible volume of water thunders over the falls every minute, making it not only a natural wonder but also a massive source of hydroelectric power for both the U.S. and Canada. After its plunge, the water continues into Lake Ontario and eventually out the St. Lawrence River to the Atlantic Ocean.