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Reservoir Containment Dike Failure
The chance of containment dike failure is considered to be exceptionally rare. The following information provides residents with awareness of the containment dike flooding risk, the types of warnings that may be given, and provides suggested safety measures to take during the event of a flood.
In the event the western containment dikes along Folsom Lake fail, areas within the City of Roseville have the potential to be significantly impacted by flooding. A lesser risk comes from the failure of the containment dike located at the Miners Ravine Off-Channel Detention Basin.
Roseville has made significant investments in developing flood mitigation improvements and instituting a comprehensive floodplain management program. As a result, Roseville is the only city in the United States to hold a Class I rating as part of FEMA's Community Rating System.
Folsom Lake Containment Dikes
Six dikes, increasing in size from north to south, fill gaps along the western edge of Folsom Lake. The northernmost dikes are relatively low height embankments above the normal operating range of the lake. The degree of flooding impact to the Roseville area would be related to the water level of the lake at the time of any containment dike failure.
Recent improvements to Folsom Dam, including the new auxiliary spillway construction, will improve Folsom Dam's flood control ability. The auxiliary spillway will allow for the increased release of water during an extreme storm event, thus reducing the risk of dam or dike overtopping. To learn more about the improvements to Folsom Dam, please visit the U.S. Department of the Interior - Bureau of Reclamation website.
To learn more about the containment dikes along the western edge of Folsom Lake, view the City of Roseville's Multi-Hazard Mitigation Plan.
Miners Ravine Off-Channel Detention Basin
The Miners Ravine Off-Channel Detention Basin is a regional flood control facility owned and operated by the Placer County Flood Control and Water Conservation District (PCFCWCD). The City of Roseville is a member agency of the PCFCWCD.
This detention basin only receives inflows for short durations during infrequent storm events, and only when storm water in the Miners Ravine channel is higher than the intake gates upstream from the basin. Therefore, the embankment is not exposed to water pressure during non-storm events. The impact to the Roseville area would amount to a 6-inch increase in flood levels within the existing 100-year floodplain.
The City of Roseville is now using an emergency notification system called Alert Roseville to notify the public in an emergency. To learn more and register your number(s) and/or e-mail, visit www.roseville.ca.us/AlertRoseville. All contact information is confidential.
In addition to Alert Roseville, the City of Roseville has many ways of communicating with the public in an emergency.
- Local news media
- Twitter and Facebook
- E-mails sent to subscribers of the Public Safety e-notifications
- Electronic message signs along main roadways
- Emergency Information Phone Line: (916) 774-5812
- City of Roseville TV (Comcast Channel 14 and Consolidated Communications Channel 73)
- AM Radio 530
Protect yourself and your family by being aware of hazards and taking steps to be prepared by reviewing evacuation procedures and routes (shown below) and safety information specific to flooding
- Folsom Containment Dike Evacuation Map
- Miners Ravine Containment Dike Failure Map