San Gabriel Reservoir


In 2022, Ames Construction began a multi-year effort to remove 5 million cubic yards of sediment from the San Gabriel Reservoir in California.

The emergency restoration project was triggered by the 2020 Bobcat Fire and subsequent rains that washed debris into the reservoir, reducing its capacity. The reservoir provides flood control and groundwater recharge for the San Gabriel Valley and Greater Los Angeles.

To begin work, millions of gallons of water from behind the dam were removed by Los Angeles County and Ames to expose the saturated sediment for excavation. Additionally, Ames diverted two streams by adding a series of berms and laying approximately 2 miles of pipe. All diversions and pipe crossings are approved by biologists who are working to ensure that fish are safely removed and relocated.

Saturated sediment is excavated and transported to drying stockpiles, where crews work the material to optimum conditions prior to placement and compaction. Once at optimum moisture, the sediment is transported to the fill placement site. In the project’s second season, crews installed a 2-mile-long conveyor belt to move material to the permanent fill site, reducing the project’s use of haul trucks.

Ames is also rehabilitating the dam’s main outlet and sluiceway tower and tunnel.

Learn more: Los Angeles County

Markets: Water Resources, Reservoirs, Environmental, Dams

Location: Los Angeles County, California

Client: Los Angeles County Public Works

Completion: In progress


  • 5 million cubic yards of sediment to be removed from the reservoir
  • 2-mile-long conveyor belt to transport material
  • 2 miles of pipe to divert two streams