Seven Oaks Dam, Embankment dam in San Bernardino County, California, United States

Seven Oaks Dam is a 550-foot (170 m) earth and rock fill embankment dam across the Santa Ana River in the San Bernardino Mountains, about 4 miles (6.4 km) northeast of Redlands. The arched structure is 2,980 feet (910 m) long, 40 feet (12 m) wide at the crest and over 2,200 feet (670 m) wide at its base, and it impounds Seven Oaks Reservoir in the San Bernardino National Forest.

The U.S. Army Corps of Engineers proposed the dam as part of the Santa Ana River Mainstem Project, replacing the controversial Mentone Dam site above the San Andreas Fault. Construction ran from 1994 to 2000, when the dam was dedicated in January. The final cost reached $450 million, with the federal government covering 70.47% and Orange County 27.09%.

The dam sits at the edge of the San Bernardino National Forest, and the trails nearby draw hikers who follow the Santa Ana River upstream. For people living in the valleys below, the structure is a visible reminder that the land around them was shaped by repeated flooding.

The dam is about 4 miles (6.4 km) northeast of Redlands, reached by mountain roads in the San Bernardino National Forest that weather can affect, so check the route first. The crest is 40 feet (12 m) wide and 2,980 feet (910 m) long. The reservoir is often partly or entirely dry in the dry season, so the water level varies greatly.

The dam was built to withstand a major earthquake because it sits just a short distance from one of California's most active fault lines. This requirement made it one of the most technically demanding earthen dams ever built in the United States.