San Clemente Dam

San Clemente Dam during normal flows.

This page gives a short history of the San Clemente Dam and description of the planned dam removal project and its environmental impact and related issues and controversies.

History

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. Later the dam was purchased by 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 dam to California American Water for $42 million. .

Geology and Ecology of Carmel River Watershed

Geology and Sedimentation

San Clemente Dam being overtopped by highly sedimented flow during a rain storm. Image: NOAA

The Carmel River watershed is on a highly erodable geological formation (filler to be flushed out). Although the dam was built in 1921, by 1947 it was 25% silted and is now 98% silted.

Seismic Considerations

Located near the Tularcitos fault, the San Clemente Dam is vulnerable a catastrophic failure due to an earthquake. With the dam having reached its expected useful life and with 1500 homes below the dam under threat, in 2006 the California Department of Water Resources decided that action had to be taken in order to mitigate the danger by either removing or reinforcing the dam.

Threatened Species

• Central Coast steelhead trout. The Carmel River lies within the South-Central California Coast (SCCC) Evolutionarily Significant Unit (ESU) which has been classified as "threatened". The [ http://en.wikipedia.org/wiki/California_Department_of_Fish_and_Wildlife California Department of Fish and Game (CDFG)] is a stakeholder in the process and is one of the stakeholders in the dam removeal process. The CDFG is responsible for managing and maintaining a healthy steelhead population and are working on restoration of the population to historic level on the Carmel River.

• California red-legged frog

Dam Removal

Reasons for Dam Removal

• 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 .
• 2006 - 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.
• 2008 - DSOD stated the Reroute and Removal project would address the dam's public safety issues and other environmental impacts caused by the dam making it the best option for all stakeholders .

Benefits of reroute plan:

• Permanent resolution to the dam safety concern
• Access for endangered steelhead trout to 25+ miles of spawning and rearing habitat
• Restoration of sediment to the downstream reach of the river and Carmel River State Beach
• Restored ecological connectivity for riparian and aquatic habitats

Carmel River Reroute and Dam Removal Project description:

• Construction Access Roads- In order to carry out the CRRDR access roads are being constructed off of Carmel Valley Road after Carmel Valley Village and before the Sleepy Hollow turn-off.
• Diversion Dike
• Reroute Channel and Upper Carmel River Reach - The Carmel river will be 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 created by the diversion channel will be used to block the sedimented reach of Carmel and divert the river into the San Clemente reach.
• Combined Flow Reach and Upper San Clemente Creek Reach
• Stabilized Sediment Slope
• Sediment Stockpile
• Dam Removal
• Old Carmel River Dam (OCRD) Removal

Timeline

As of March 2013, construction is set to begin in 2013, and the estimated completion is set for 2015. Access roads are under construction at this time.

Links

• The Carmel River Watershed

• Maps of the Carmel River Watershed

• San Clemente Dam Removal Consortium

• Coho Salmon Crisis in the Central California Coast ESU

• Carmel River Lagoon

• CalAm Use of Carmel River Groundwater Basin

• Los Padres Reservoir Capacity Issues

• ENVS 560/L Watershed Systems

Disclaimer

This page may contain students's 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.