Winterhaven (formerly, Karmack) is a census-designated place (CDP) in Imperial County, California, United States. Winterhaven is located 6.5 miles (10 km) east of Pilot Knob, The population was 529 at the 2000 census. It is part of the 'El Centro, California Metropolitan Statistical Area'. North of Interstate 8 and bordering Yuma, Arizona, the town is partly Quechan Indian reservation. The Colorado River is the town's eastern border.