A Legacy in Stone and Concrete: The Old Carmel River and San Clemente Dams This brochure provides an excellent visual and descriptive overview of the history of development on the Monterey Peninsula and development of the Old Carmel River and San Clemente Dams.
San Clemente Dam is a 106-foot-high concrete arch dam located approximately 18.5 miles from the Pacific Ocean on the Carmel River in Monterey County (see Figure below). The confluence of the Carmel River and San Clemente Creek is located just upstream ofthe dam. When the dam was constructed in 1921, it had a reservoir storage capacity of approximately 1,425 acre-feet. Today the reservoir has been filled by more than 2.5 million cubic yards of sediment, leaving a reservoir storage capacity of approximately 70 acre-feet as of 2008. California American Water (CAW) owns and operates the dam. San Clemente Dam currently serves no useful purpose now that water is no longer diverted from upstream of the dam.
The California Department of Water Resources (CDWR) Division of the Safety of Dams issued a safety order for the dam structure in the early 1990s, determining that the structure could potentially fail in the event of either the maximum credible earthquake or probable maximum flood (PMF). In 2006, CDWR released a Draft Environmental Impact Report/Environmental Impact Statement (EIR/S) for the San Clemente Dam Seismic Safety Project that evaluated five alternatives for addressing the safety issue, including CAW’s then- preferred approach of Dam Strengthening, as well as the alternative Carmel River Reroute & San Clemente Dam (CRRDR) option.
Strengthening the dam would resolve the public safety issues, but would not address other issues related to the dam such as impaired access for steelhead to 25 miles of upstream spawning and rearing habitat, disruption of sediment transport to the lower river and Carmel River beach, and ecological discontinuity of aquatic and riparian habitats. Removing the dam would resolve these issues and provide significant benefits to both steelhead and California red-legged frog (CRLF). For these reasons, the California State Coastal Conservancy (as the lead for the State of California), National Oceanic and Atmospheric Administration’s (NOAA’s) National Marine Fisheries Service, and the Planning and Conservation League Foundation worked with CAW to develop a feasible approach to cooperatively implement the CRRDR option. In December 2007, CDWR certified the Final EIR/S, and in February 2008, CDWR indicated that the dam safety issue could be addressed through implementation of the CRRDR project.