San Clemente Dam
This page gives a short history of the former San Clemente Dam and a description of the completed dam removal project, its environmental impact, and related issues and controversies. As of 2017, the project ranked as the largest dam removal project in California history.
- 1 History
- 2 Geology and Ecology of Carmel River Watershed
- 3 Dam Removal
- 4 Stakeholders
- 5 References
- 6 Links
- 7 Disclaimer
The San Clemente Dam was built in 1921 by a local businessman Samuel Morse on the Carmel River to supply the water needs of Monterey's growing population and tourism industry. When it was first built, the dam had a reservoir storage capacity of approximately 1,425 acre-feet. 
In 1930, Morse sold the dam to Chester Loveland, who owned the California Water and Telephone Company (CW&T). To meet the needs of the growing population and increasing demand from the sardine processing industry in Monterey, CW&T built the Los Padres Dam upstream from San Clemente Dam in 1948. In 1966 CW&T sold the San Clemente Dam to California American Water Company (CalAm) for $42 million. .
Geology and Ecology of Carmel River Watershed
Geology and Sedimentation
Parts of the the Carmel River are surrounded by steep slopes of fractured granite that are subject to severe erosion during heavy precipitation events (Image 2). The rugged terrain and arid climate of the Santa Lucia Mountains make wildfires difficult to control, leading to a range of land and water management challenges in the wake of fire. In specific, numerous local wildfires contributed substantially to a decrease in reservoir capacity at the former San Clemente Dam site.  Although the dam was built in 1921, by 1947 it was 25% silted and by 2012 it was 98% silted. 
Located near the Cachagua and Tularcitos faultiness,  the San Clemente Dam was deemed vulnerable to a catastrophic failure in the event of a "maximum credible earthquake" by the California Department of Water Resources (DWR) Division of the Safety of Dams. With the dam having reached the end of its expected useful life and 1500 homes and other structures below the dam under threat, in 2006 the DWR decided that action had to be taken to mitigate the danger by either removing or reinforcing the dam. While CalAm proposed reinforcing the dam, other stakeholders including the NOAA Marine Fisheries Service (NMFS) advocated removal in order to benefit local species subject to population decline: the California Red-legged frog and coastal steelhead. In 2013 the San Clemente Dam was commissioned to be removed. 
There are two, federally-listed species in the Carmel River Watershed that would likely benefit from a restored river in place of the dam.
- The Central Coast Steelhead trout population, endemic to the Carmel River, are within the South-Central California Coast (SCCC) Evolutionarily Significant Unit (ESU). The SCCC ESU has been classified as "threatened". The California Department of Fish and Game (CDFW) is responsible for managing and maintaining a healthy steelhead population and are working on restoration of the population to historic levels on the Carmel River. 
- The California Red-legged frog was listed as threatened in 1996 by the U.S. Fish and Wildlife Service. The red-legged frog is found in different parts of the watershed and the health of the population is unclear and development and water extraction activities have required additional review to ensure compliance with the Endangered Species Act.
Granite Construction, a locally-based construction management firm, served as the general contractor for the dam removal. Before the dam was taken down, they worked for two years to prepare the site by rerouting the river and relocating reservoir sediments. The San Clemente Dam was removed in the summer of 2015. 
Reasons for Dam Removal
In the 1990s, California Department of Water Resources (DWR) Division of the Safety of Dams(DSOD) issued a safety order which determined that in the event of the maximum credible earthquake or probable maximum flood the dam would potentially fail, creating a public safetly issue. After this report the San Clemente Dam was listed as a high priority public safety issue. An Environmental Impact Report was prepared to explore the best method for addressing the public safety issues. In 2006 the DWR released a Draft Environmental Impact Report/Environmental Impact Statement (EIR/EIS). The EIR explored CalAm's preferred option of strengthening the Dam and four alternative projects, including the Carmel River Reroute and Dam Removal (CRRDR) option. The CRRDR option had several ecological benefits that the Dam Strengthening option did not. In 2008, the DSOD stated that the CRRDR project would address the dam's public safety and environmental impact issues, making it the best option for all stakeholders.
Carmel River Reroute and Dam Removal (CRRDR) Project:
The Carmel River Reroute and Dam Removal (CRRDR) was expected to provide several benefits for the Carmel River including:
- Permanent resolution to the dam safety concern
- Access for endangered steelhead trout to 25+ miles of spawning and rearing habitat
- California red-legged frog habitat improvement
- Restoration of sediment to the downstream reach of the river and Carmel River State Beach
- Restored ecological connectivity for riparian and aquatic habitats.
The Carmel river was rerouted into the adjacent San Clemente Creek, a half mile upstream of the dam, by cutting a diversion channel through a narrow ridge separating the two channels. The rock excavated during construction of the diversion channel was used to block off the sedimented reach of the Carmel above the dam and is referred to as the diversion dike (Image 3). The sediment that had accumulated in the channel directly behind the dam was excavated and transferred to the upper portion of the Carmel reach and stabilized to prevent erosion during high flows.
The reach of the San Clemente river downstream of the diversion dike was converted to a system of step pools. The restoration was intended to create a riparian corridor and seasonal ponds that California red-legged frogs can use as habitat.In 2014, the San Clemente Dam and fish ladder was removed. Once removed, the Old San Clemente Dam (1800 ft downstream) was notched to improve steelhead passage and the overall river stability.
The eventual plan is for CalAm to transfer the completed project to the Monterey Peninsula Regional Park District. Adding this portion of land to the Park District will link Garland Regional Park and the San Clemente Open Space. The property use will be restricted for watershed conservation and compatible public access .
The total cost of the project was 83 million dollars. California American Water Company (CalAm) contributed 49 million dollars, the original cost to stabilize the dam in-place. The remaining funds were contributed by numerous other agencies such as California State Coastal Conservancy (Conservancy), National Marine Fisheries Service (NMFS), and the Planning and Conservation League Foundation .
Below are the key project goals from 2013 to 2016. The project was completed on schedule in 2016. 
- Access road design and construct
- Finalized diversion system design
- Obtain permits and government approval
- Wildlife relocation along new Access Road and Project Site
- Site preparation including clearing, fencing, and construction access roads
- Geotechnical investigations111
- Partial construction of Diversion System
- Site earthwork design
- Complete construction of Diversion System
- Construct Diversion Dike
- Construct the Re-Route Channel
- Construct the Sediment Stockpile
- Partial excavation of the Combined Flow Reach
- Partial San Clemente Dam removal
- Additional geotechnical investigation
- Construct the Stabilized Sediment Slope
- Finalize Channel and Habitat restoration design
- Complete demolition of the San Clemente Dam
- Construction of the Combined Flow Reach Channel
- Initial habitat restoration
- Construct permanent bridge over Carmel River
- Completion of habitat restoration & irrigation system
- Removal of the Old Carmel River Dam
- Construct the Sleepy Hollow Ford Bridge
- Start of monitoring and habitat establishment periods
Heavy precipitation events in the wake of the Soberanes Fire, during the winter of water-year 2017, caused extreme flood events that completely rearranged the 54 engineered step pools in the San Clemente River reroute channel. The step-pool system has not been reconstructed. These high flows also resulted in sediment from the former San Clemente Dam reservoir being transported throughout the course of the Carmel River, with significant aggradation and pool filling found as far downstream as the river mouth. 
Post Removal Monitoring
Several post-dam removal monitoring criteria are established in the Mitigation Monitoring and Reporting Program (MMRP). These monitoring and mitigation criteria are the responsibility of Cal-Am Water, and fall into the categories of:
- Geology and soils
- Hydrology and water resources
- Water quality
- Vegetation and wildlife
- Air quality
- Greenhouse gas emissions
- Traffic and circulation
- Cultural resources
- Visual Resources
To date, much of the information on this process is not public, but several monitoring efforts have produced public documents:
- Fish passage studies by California State University Monterey Bay (CSUMB) and AECOM
- Morphological Monitoring of the Carmel River Channel by California State University Monterey Bay (CSUMB) and by Harrison et al.
- Large Woody Debris on the Carmel River From Camp Steffani To Carmel Lagoon by California State University Monterey Bay (CSUMB)  
Various private and public organizations have played a role in the dam removal project. Some of these are:
- California American Water Company (CalAm)
- California Public Utilities Commission (CPUC)
- Monterey Peninsula Water Management District (MPWMD)
- California Department of Fish and Wildlife (CDFW)
- National Oceanic and Atmospheric Administration (NOAA)
- California State Coastal Conservancy
- Rana Creek Ecological Design
- Camp Stefanie residents
- Downstream private land owners in Carmel Valley
- CalAm rate payers
- San Clemente Dam Removal & Carmel River Reroute Project Website Project Overview
- San Clemente Dam Removal & Carmel River Reroute Project Website Background & History
- Keith Vandevere, Visual Voices Threat of the Dam. Water Over the Dam
- Carmel River Watershed Council, 2010. Carmel River History.
- Alberola GJ. 2012. Active Projects in the Carmel River Watershed, prepared for The Carmel River Watershed Conservancy.
- (USGS) Kapple GW, Mitten HT, Durbin TJ, and Johnson MJ. 1984. Analysis of the Carmel Valley Alluvial Ground-Water Basin, Monterey County, CA, Water-Resources Investigations Report 83-4280.
- Final Supplement to the Environmental Impact Report: San Clemente Dam Seismic Safety Project
- Resource Conservation District of Monterey County& members of the Carmel River Task Force Watershed Stewardship Manual
- San Clemente Dam Removal & Carmel River Reroute Project Website Home
- California State Coastal Conservancy. Date unknown. San Clemente Removal Project Description
- San Clemente Dam Removal & Carmel River Reroute Project Website Project Funding
- San Clemente Dam Removal & Carmel River Reroute Project Website Schedule
- Schmalz D. 2017. High winter flows remade the new Carmel River channel, that might be a good thing. Monterey County Weekly Online.
- Harrison LR, East AE, Smith DP, Logan JB, Bond RM, Nicol CL, Williams TH, Boughton DA, Chow K, Luna L. 2018. River response to large-dam removal in a Mediterranean hydroclimatic setting: Carmel River, California, USA: River response to large-dam removal. Earth Surface Processes and Landforms. 10.1002/esp.4464.
- DWR Division of Safety Dams. 2012. Mitigation Monitoring and Reporting Program for the San Clemente Dam Seismic Safety Project.
- Smith D., Bogdan, M., Klein J., Terzoli, A., and McNeely S. 2018. Carmel River Reroute and Dam Removal Fish Passage Assessment (Summer 2018). Watershed Institute, California State University Monterey Bay, Publication No. WI-2018-07
- Chow K, Luna L, Delorge A, and Smith D. 2016. 2015 Pre-San Clemente Dam Removal Morphological Monitoring of the Carmel River Channel in Monterey County, California. The Watershed Institute, California State University Monterey Bay, Publication No. WI-2016-01, 50 pp.
- Steinmetz C. and Smith D. 2018. 2017 Post-San Clemente Dam Removal Morphological Monitoring of the Carmel River Channel in Monterey County, California. The Watershed Institute, California State University Monterey Bay, Publication No. WI-2018-03, 47 pp.
- Klein J, Bogdan M, Steinmetz C, Kwan-Davis R, Price M, and Smith D. 2019. 2018 Post-San Clemente Dam Removal Morphological Monitoring of the Carmel River Channel in Monterey County, California. The Watershed Institute, California State University Monterey Bay, Publication No. WI-2019-02, 68 pp.
- Carter L, Fields J, Smith DP. 2016. Large Woody Debris on the Carmel River from Camp Steffani to the Carmel Lagoon, Fall 2015: Watershed Institute, California State University Monterey Bay, Publication No. WI-2016-05, 25 pp.
- Steinmetz, C. and Smith DP. 2018. Large Woody Debris on the Carmel River from the Former Dam Keeper's House to Carmel Lagoon, Fall 2017: Watershed Institute, California State University Monterey Bay, Publication No. WI-2018-02, 27 pp.
This page may contain student work completed as part of assigned coursework. It may not be accurate. It does not necessarily reflect the opinion or policy of CSUMB, its staff, or students.