“With WSC’s help, we brought all agencies back to the table. By conducting a comprehensive risk assessment, partners could see each solution from all perspectives—risk, cost, environmental impact, as well as short- and long-term value. That allowed the partners to move to a conversation focused on value.”
Central Coast Regional Manager
As of December 2015, the 106-foot-tall San Clemente Dam had been completely removed, allowing California’s Carmel River to flow freely once again. Endangered steelhead could once again access more than 25 miles of habitat, while naturally accumulating sediment could flow downstream and replenish Carmel River Beach. But for nearly 100 years, this had not been the case.
In 1912, the San Clemente Dam was constructed on the Carmel River to provide water supply for the Monterey Peninsula. Yet by the early 2000’s, decades of sediment buildup had reduced its storage capacity to only five percent. An existing fish ladder, already one of the steepest in the country, was also ineffective. Further, the dam’s seismic risk was significant; if it failed, downstream impact could be devastating. Decision makers could buttress the dam to keep sediment in-place (at the tune of $49M), or remove the dam and the sediment altogether, providing a literal gateway to a healthier river and watershed.
Initially, the Dam’s owner, California American Water (Cal Am), was required to approve the “lowest cost, shortest timeline” buttress option, which left several challenges unresolved—including the opportunity for watershed and ecosystem restoration. By 2007, Cal Am was at an impasse. While well intentioned, each of its state and federal partners had conflicting positions on the “right” solution.
“With WSC’s help, we brought all agencies back to the table,” described Trish Chapman, Central Coast Regional Manager of the California State Coastal Conservancy. “By conducting a comprehensive risk assessment, partners could see each solution from all perspectives—risk, cost, environmental impact, as well as short- and long-term value. That allowed the partners to move to a conversation focused on value.”
The collaborative risk assessment ultimately pointed to the removal of the dam and rerouting of the Carmel River as the optimal solution. Removal of the 10-story concrete dam would be the largest efforts of its kind in California history and required close partnership between public and private agencies, including Cal Am, the California State Coastal Conservancy, National Marine Fisheries Service, and the Planning and Conservation League Foundation.
As a critical project partner, WSC coordinated plans among project partners. Plans for careful phasing and execution were developed in coordination with multiple contractors, consultants, and regulatory agencies. The plan involved three critical phases using a design/build approach: stabilizing the sediment trapped behind the dam, re-routing the river to connect with San Clemente Creek, and removal of the dam.
Once the dam was removed, river restoration began. Installation of boulders, wood structures, channels, pools and vegetation provided healthy habitat for several endangered species including Steelhead and California red-legged frogs. WSC remained the construction management consultant during the 10-year period of monitoring and habitat establishment.
Five years after the dam was removed, the Carmel River is returning to its wild state, and the fish population is rebounding. Steelhead numbers in the upper watershed appear to be slowly increasing as steelhead are now able to travel upstream to more of historic spawning grounds. In 2019 more than 127 made it to Los Padres Dam, located five miles above the former dam site. Other species, such as lampreys, are also returning.
As more aging dams are decommissioned across the United States (more than 80 were removed in 2019 alone) the success of the San Clemente Dam removal, and the corresponding restoration of the Carmel River, is serving as a model of effective public-private partnerships on similar projects throughout the country.