The largest impounded body of water in El Salvador, at 135 square miles, is Cerron Grande Reservoir, which was created by a hydroelectric dam on the Lempa River.
Although it is the largest lake in the country, a limnological purist would refer to Cerron Grande as the largest manmade lake.
Several such lakes exist in El Salvador, the largest of which is Ilopango, at 70 square miles of surface area. With a relatively small surface area of only 17 square miles, the largest natural lake in the country is Lago Guija.