Facts - San Clemente Dam

  • Location: 18 miles from the ocean in the Carmel Valley (Monterey County, California)

  • Owner: California American Water

  • Date Constructed: 1912

  • Purpose: Water supply

  • Height: 106 ft tall 

  • Reservoir Capacity (Design): 1,425 acre-feet

  • Reservoir Capacity (At end of life): 70 acre-feet (5%)

  • Amount of Sediment in Reservoir (At end of life): 2.5 million cubic yards (or 250,000 dump trucks)

  • Year Dam Removed: 2015

  • Years to Remove: 15 years planning / 3 years de-construction

  • Dam Removal Cost: $86.3 million

  • Funders: California American Water ($51M), State of California ($29.2M), federal funds ($2.5M), settlement funds ($2.2M), the Nature Conservancy ($1M), Resources Legacy Fund Foundation ($0.4M)

  • Miles of Spawning Habitat Upstream: 25 miles, on mainstem and tributaries before Los Padres Dam

  • Project Partners: California American Water, State Coastal Conservancy, National Marine Fisheries Service

  • Largest dam removal project in California at time of removal

Timelime

1921 San Clemente Dam built 

1991 Dam declared seismically unsafe by state inspectors from California Department of Water Resources Division of Safety of Dams

1999 Carmel River listed as one of North America’s 10 most endangered rivers (American Rivers)

2006 Environmental studies prepared offering several alternatives for bringing the dam into compliance with safety standards (including removing it, buttressing it, and cutting it down partway)

2007 Additional studies confirm feasibility of dam removal option

2009 Dam removal and river re-route option chosen 

2011 Preliminary designs completed and project approval received from California Public Utilities Commission

2013 Construction begins

2015 San Clemente Dam removed

2016 Old Carmel River Dam removed

2017 Large flood reorganizes river channel

2019 127 steelhead counted at Los Padres Dam, five miles upstream

Frequently Asked Questions

1. Where was the San Clemente Dam located?

 

18 miles upstream on the Carmel River in the Carmel Valley (Monterey County, California).

 

 

 

 

 

 

 

2. What are the benefits of the project?
The San Clemente Dam Removal and Carmel River Reroute Project represents one of the best opportunities for river restoration on California’s Central Coast. Permanently removing the dam eliminated the public safety risk posed by San Clemente Dam, which was declared seismically unsafe by the State of California and threatened 1500 homes and other buildings.

The removal of the dam will also aid in the recovery of South-Central California Coast steelhead, a threatened species, by providing unimpaired access to over 25 miles of spawning and rearing habitat. The National Marine Fisheries Service has determined restoration of the Carmel River steelhead population is critical to the recovery of the species.

Additional benefits of the project include: restoring the natural sediment regime which will reduce channel incision and beach erosion that now contribute to destabilization of homes, roads and infrastructure; improving habitat for threatened California Red-Legged Frogs; and expanding public recreation opportunities in the region by preserving over 900 acres of watershed lands, resulting in over 5400 acres of contiguous park land.

3. Did San Clemente Dam provide flood protection?
San Clemente Dam never provided any flood control, and its removal will not affect the volume or timing of flood flows on the river. The project team completed sediment transport and flood modeling studies to verify that removal of the dam would not exacerbate the existing downstream flooding problems.

 

4. Will the project affect water supply for Monterey Peninsula residents?
There will be no change to the water supply available to Peninsula residents as a result of removing the dam. For several years prior to its removal, the primary purpose of the San Clemente Dam had been as a diversion point for Carmel River water. The dam’s reservoir was over 95% full of sediment when removed, which had greatly impaired its ability to continue functioning as a diversion point. All water supplies from the Carmel River are now diverted from groundwater wells situated along the river that pump from the alluvial aquifer.

 

5. What will happen to the land after the dam is removed and the river restoration is complete?
925 acres of California American Water property will be transferred to the U.S. Department of Interior’s Bureau of Land Management (BLM). The State Coastal Conservancy is working with BLM and the Monterey Peninsula Regional Parks District (MPRPD) to develop a long-term management plan for the property that will include public access and recreational trails on the property.

 

6. Why was the river rerouted into San Clemente Creek?
2.5 million cubic yards of sediment had built up behind the dam structure over 85 years. Allowing this sediment to flow downstream could have significantly increased flood risks and potential damage to downstream homes and businesses. Other options such as trucking the sediment out of the area or moving the sediment to another site were determined to be infeasible because of cost, difficult access to the site, environmental impacts, and lengthy timelines for undertaking these activities. The rerouting of the Carmel River into San Clemente Creek moved the confluence of these two waterways upstream by one-half mile. This allows the sediment to stay in place without risk of the river transporting the sediment downstream. The sediment area is being restored into a vegetated landscape that is integrated into the natural contours of the watershed.

 

7. How was the project funded?
The total project cost was $86.3 million. California American Water (CAW) is contributing $51 million, which is equivalent to the lowest cost project for addressing the dam’s seismic safety issue (buttressing the dam). The California State Coastal Conservancy and National Marine Fisheries Service raised the additional $35.3 million for project implementation through public and private sources including $29.2 million in state funds, $2.5 million in federal funds, $1M from The Nature Conservancy, and $0.4 million from the Resources Legacy Fund Foundation.