sentences:  This interconnected wetland still supports up to 3.7 million migrating birds per year.In wet years, the two lakes would connect to Upper Klamath Lake, forming one huge body of water.These lakes occupy the basin that was prehistorically occupied by Lake Modoc, a freshwater lake that covered the entire Upper Klamath Basin, or 7% of the watershed - an area three times larger than the massive Salton Sea in southern California.