Which Great Lake has the shortest water retention time?

Lake Erie has the shortest water retention time of the five Great Lakes, at about 2.6 years.

Water retention time is the average length of time water remains in a lake before flowing out. Erie’s relatively small volume and substantial inflow from the upper Great Lakes allow it to be renewed much faster than the other lakes.

Water enters Lake Erie mainly through the Detroit River, which carries water from Lake Huron, Lake Michigan, and Lake Superior via the connecting waterways. It leaves through the Niagara River toward Lake Ontario. This flow makes Erie an important middle link in the Great Lakes drainage system.

Lake Erie is also the shallowest Great Lake, with an average depth of about 19 metres. Its shallowness contributes to rapid warming, intense storms, and historically serious nutrient and algae problems, although water quality has improved in several areas since major pollution-control measures were introduced.