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Slow Rise Flooding

The Sacramento, Feather and Bear Rivers, flowing along the boundaries of Sutter County, are subject to heavy runoff from the mountains surrounding the Sacramento Valley and have flooded throughout the past. Additionally, the Sutter By-Pass, a floodwater relief channel for the Sacramento River, flows north-to-south through the center of Sutter County. All of these waterways are controlled by levees.

Flooding While most of Sutter County would be threatened by inundation as a result of dam failure at several Northern California reservoirs (e.g., Oroville and Shasta Dams), the highest risk disaster threat to Sutter County is flooding from heavy winter storms. This type of incident follows an extended period of heavy rainfall and steadily rising river levels over a period of days; hence the name "slow rise flood." Flooding could result from levee failure or overtopping. This type of event is always accompanied by the back-up of surface drainage flows in low-lying areas.

Sutter County has a plan to alert its citizens to the hazards from flooding; however, everyone must take responsibility for their own individual and family planning and preparation. Further, it is a good idea to be at least minimally prepared at all times for a sudden emergency. The American Red Cross website carries a guide to personal emergency preparation. You may wish to consult the site and use it to decide the appropriate level of preparation for you and your family as an on-going precaution for all types of emergencies.

Flooding Warning System

Sutter County utilizes three emergency activation phases in its flood warning system.

Planning and Preparation Phase:
In this phase, the river has flowed over the banks of the main channel, and government assumes a readiness condition.

Ready for Action Phase:
All those in the affected area should be ready for an Advisory Evacuation Notice or Mandatory Evacuation Order to be given at any time. Any last-minute preparations should be made.

(An Advisory Evacuation Notice is issued when conditions exist which indicate a Mandatory Evaluation order may be given in the near future. The threat to lives is not yet imminent but there is potential for rapidly changing conditions to develop into a serious threat. Residents are advised to leave the area. A Mandatory Evacuation is ordered when conditions exist that seriously endanger lives. The danger is imminent. All non-essential persons are ordered to immediately leave the area via the described evacuation routes.)

Emergency Phase:
At this point, the likelihood of a mandatory evacuation of the affected area becomes much greater. It will probably be called in the near future, and there will be little or no time for individuals or business owners to take further protective actions. It is crucial for persons to pay close attention to emergency information provided by the County and the Cities.

To determine which phase is in effect, please listen to a local radio or television station (see following paragraph) for the reported river levels and then review the table below which portrays the river levels, in feet, for the three emergency activation phases for the various areas of the county.

Emergency Activation Phases

Sutter County Slow Rise River Flood Threat Outline of Emergency Activation Phases
Basin Monitoring Station Planning & Preparation Phase Ready for Action Phase Emergency Phase
Meridian Sutter By-Pass @ Longbridge <50.5 >=50.5 >56.6
Meridian Sacramento River @ Colusa Bridge <66.5 >=66.5 >70.0
Robbins Sacramento River @ Tisdale <51.0 >=51.0 54.0
Robbins Sacramento River @ Knights Landing <40.0 >=40.0 >43.5
Southeast County Basins Feather River @ Nicolaus <42.6 >=42.6 >46.4
Yuba City & Live Oak Basins Feather River @ 5th St. Bridge <70.0 >=70.0 >77.0

There are numerous factors that contribute to the flood danger present at any given time. For example, the forecasted weather, the forecasted river crest, the releases from upstream dams, the length of time water has been on the levee, the number of times water has been on the levee in the season, the time of day, and the number of people to be evacuated are all considered before an evacuation is ordered.

Because much of Sutter County is low-lying and protected by levees, individuals and families should have a plan for where they would go and what they would take should a mandatory evacuation be called. It may be expected that you will have to leave Sutter County altogether. Once you evacuate the area, you will not be able to return until the evacuation order has been cancelled. You should also monitor local radio and television stations for road and bridge closures. In addition, CalTrans provides recorded road information and highway conditions at (800) 427-ROAD (7623); just know your highway numbers before you call.