Littlerock Dam, Gravity dam in Los Angeles County, California, United States

Littlerock Dam is a concrete gravity dam on Little Rock Creek, about 5 mi (8 km) south of Palmdale in Los Angeles County. It stands 124 ft (38 m) high and spans 576 ft (176 m) across the canyon, forming a 108-acre reservoir. Its face was strengthened with roller-compacted concrete in 1994, hiding the original multiple-arch design, though the arches remain visible on the back face when the water level is low.

The dam was constructed in 1924 by engineer John S. Eastwood and was at that time the tallest structure of its kind in the world. Its innovative multi-arch design represented a breakthrough in dam engineering techniques.

The dam supported regional agricultural development by providing water supply to South Antelope Valley farmers and residents for multiple generations.

The dam, reservoir and surrounding facilities have been closed to the public since 2015, and there are no plans to reopen them. The site lies about 5 mi (8 km) south of Palmdale, reached via Little Rock Creek Road off the Pearblossom Highway corridor. The reservoir is under a California OEHHA safe-eating advisory for fish due to mercury or PCBs.

The 1994 renovation hid the original multiple-arch design behind roller-compacted concrete, but the arches remain visible on the back face of the dam when the reservoir level is low. The same work raised the dam 12 ft and added a new spillway, bringing capacity to 3,700 acre-feet.