The California Division of Safety of Dams imposed a seismic restriction on the Big Tujunga Dam in 2004 that limited the long-term storage to 1,484 acre/foot. The rehabilitation and spillway modification project, performed by AECOM (legacy Shimmick), restored the dam’s original storage capacity to meet the new requirements.

The working included cleaning the foundation; placing mass concrete; modifying the spillway; removing and replacing the dam crest and appurtenant structures; stabilizing the canyon walls with consolidation drilling, grouting and rock bolts; and establishing a new dam control system. The project was completed in 2011.