Tulare Lake (/tʊˈlɛəri/ ) or Tache Lake (Yokuts: Pah-áh-su, Pah-áh-sē) is an ephemeral freshwater lake in the southern San Joaquin Valley, California, United States. Historically, Tulare Lake was once the largest freshwater lake west of the Mississippi River in surface area. For thousands of years, from the Paleolithic onward, Tulare Lake was a uniquely rich area, which supported perhaps the largest population of Native Americans north of present-day Mexico.
In the second half of the 19th century, Tulare Lake was dried up by diverting its tributaries for irrigation and municipal water uses. In modern times, it is usually a dry lake with residual wetlands and marshes. The lake reappears during unusually high levels of rainfall or snowmelt as it did in 1942, 1969, 1983, 1997, 1998, and 2023.