south. Middle Alkali Lake is actually the highest at above sea level. Water will either flow south to Lower Alkali Lake at , or north to Upper Alkali Lake at . The lakes are seasonally flooded with alkaline water in most years, drying out in the summer. Annual precipitation in the basin ranges from . The average annual runoff is , which occurs mainly between March and June as snowmelt. This is enough to flood the lake beds deep; however, most of the water is either appropriated for irrigation, or evaporates in the desert heat. Formed by erosion during the Pleistocene, the alluvial deposits that make up the lake beds are up to deep at Middle Alkali Lake and hold significant amounts of groundwater. The Surprise Valley Groundwater Basin has an estimated volume of . Upper Alkali Lake The northernmost lake, Upper Alkali Lake has a drainage area of . The lake is fed by Bidwell, Second, Goose, Wilkinson, Mill, Releford and Soldier Creeks, as well as overflow from Middle Alkali Lake if the level of that lake is high enough. Middle Alkali Lake Middle Alkali Lake is the largest by both surface area and drainage area. The total catchment of Middle Alkali Lake is . Creeks flowing into the lake include Sand, Fortymile, Cedar, Deep, Granger, Milk, Cottonwood, Owl and Raider Creeks. Between Middle and Lower Alkali Lakes there is a smaller lake called Cambron Lake, fed by Highrock and Eagle Creeks. Lower Alkali Lake Lower Alkali Lake is the southernmost and smallest lake, draining . Streams feeding the lake include Emerson, Barber, and Bare Creeks, as well as occasional overflow from Middle Alkali Lake. See also List of lakes of California References Endorheic lakes of California Lakes of California Lakes of Nevada Endorheic lakes of Nevada Lakes of Modoc County, California Lakes of Washoe County, Nevada