Chester Morse Lake (originally Cedar Lake) is a lake in the upper region of the Cedar River watershed in the U.S. state of Washington. The original lake surface was 1,530 feet (466 m) above sea level, but when the river was dammed in 1900, the elevation was raised to 1,560 feet (475 m). Chester Morse Lake is more than four miles (6 km) long, and is primarily fed from the east by the north and south forks of the Cedar River, and from the south by the Rex River. The lake is part of the Seattle area water supply.