Lake Tonawanda was a prehistoric lake that existed approximately 10,000 years ago at the end of the last ice age, in Western New York, United States.

During the retreat of the glaciers, the water levels of the Great Lakes were higher.

Lake Tonawanda itself was drained into Lake Ontario by a series of falls over the escarpment, including one at present day Lockport, New York.

Subsequently Lake Erie drained over the escarpment entirely through Niagara Falls, which marks roughly the western terminus of the former lake bed.

The sinking of homes in the lakebed has been an ongoing problem in communities such as Amherst, New York.