StormReady

Lower Chicken Ranch Slough & Lower Strong Ranch Slough
Flood Risk

Chicken & Strong Ranch Woodside Condominiums Watershed Alternatives Analysis (Ford) Flood Forecasting (QPF)

Real Time Conditions Warning! This report contains provisional data from automated gauges. This data has NOT been verified for accuracy. Chicken Ranch Slough: Location Last Report Current Level Monitor Stage Flood Stage downstream of Corabel Ln cul-de-sac 16:20 11/21/2009 43.98   50.00 51.00 n/o Alta-Arden crossing, e/o Howe Av 16:34 11/21/2009 below sensor   35.50 37.90 Strong Ranch Slough: Location Last Report Current Level Monitor Stage Flood Stage s/o Cottage Wy. (Channel Ct) 16:37 11/21/2009 below sensor   44.80 45.80 s/o Hurley Av, at Clinton Rd apartment bridge 16:59 11/21/2009 24.10   31.50 33.50 East of Bell, adjacent to Northrop 16:33 11/21/2009 below sensor   29.50 32.00 D-05 Detention Basin: Location Last Report Current Level Monitor Stage Flood Stage Howe Av detention basin (D05) 16:29 11/21/2009 18.07   28.00 30.00 American River at D05 Pump Station 15:30 11/21/2009 below sensor   25.00 41.70 Equipment Last Report Status Pumps 16:03 11/21/2009 0 of 6 Pumps On Low Flow Pump 16:03 11/21/2009 Off Gates 16:03 11/21/2009 3 of 3 Gates Open

top

What Factors Contribute to Flooding in This Area?

High water in the American River in combination with an intense local rainfall event can result in flooding along Lower Strong Ranch Slough. Strong Ranch Slough rises very rapidly, giving very little warning time of potential flooding. Property owners are encouraged to pay close attention to local weather reports and should be on alert and prepared to take precautions in the event that severe weather is predicted while stages are high on the American River. Sandbagging doorways may be prudent if a significant event is forecast when American River stages are high. During an event, if Strong Ranch Slough gages hit monitor stage and are rising and radar shows more rain coming, vehicles should be moved to higher ground and belongings should be moved upstairs.

top

How Do the Detention Basin and Pump Station Reduce Flooding?

Strong Ranch Slough channel drains from El Camino Avenue at Walnut Avenue southwesterly to the County D-05 detention basin and pump station at Hurley Way and Ethan Way. The basin and pump station are located up against the American River levee. The detention basin collects the runoff and either allows it to drain through the levee through a large culvert opening in the levee, or over the levee with one small low flow pump and 6 larger high flow pumps.

When the river is low the culvert through the levee allows runoff from Strong Ranch Slough to pass through the levee and drain directly into the river by gravity. When river flows are high enough that the American River could back up through the culvert and begin to fill the basin, a large slide gate is automatically closed on the culvert to prevent this from occurring. However, closing the gate also prevents Strong Ranch Slough runoff from draining through the culvert, and thus requires that the pumps be operated to allow the basin and slough to drain.

top

What Causes the Flood Gates to Be Opened or Closed?

The D-05 gates are always open for American River elevations of 18' or less.
If the American River stage exceeds 18', the gates are opened or closed based upon a comparison of the river and basin stages. If the river stage is 0.5' or more above the basin stage, the sluice gates are closed.
If the basin stage is 0.5' or more above the river stage, the sluice gates are opened.