Lake Merced (groundwater‑fed lake)

Lake Merced is a natural freshwater lake in southwest San Francisco that is fed primarily by groundwater and springs rather than by large surface rivers. Its hydrology is strongly influenced by subsurface groundwater flow and historic groundwater extraction, and managers have undertaken projects to maintain lake levels and water quality by addressing subsurface inflows and seepage. The lake’s connection to regional groundwater makes its behavior partly subterranean in nature.