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For Immediate Use                                                                                               Contact: Reed Tollefson, (760) 378-2531
March 27, 2011                                                                                                                 

Our Ever Changing River

The South Fork Kern River cuts a new channel during the floods of December 2010

The Kern River built the South Fork Kern Valley with sediment eroded from the surrounding mountains as it meandered across the floodplain for millions of years. In December 2010 the South Fork Kern River’s channel shifted on Audubon’s Kern River Preserve. Sediment build up in the former channel caused floodwater to be diverted, cutting a new channel across a former farm field and capturing the river in what used to be an overflow channel. Flooding and channel migration are part of the natural dynamics of free flowing rivers. This is a natural event and not a problem for habitat, wildlife values or for Audubon’s property. In fact, this event can be considered positive for wildlife and habitat on the preserve. Flood events such as this rejuvenate old and create new habitat by jumpstarting the natural successional processes.

What is unknown is how we will choose to live with this river going forward. Will we choose to try to tame this river and confine it or will we build over it and let nature run its course?

The new river channel brings most of the river flow to Sierra Way roadbed as it crosses the floodplain about 0.3 miles south of the bridge and former channel. The culverts currently in place at this portion of the road will not be sufficient to carry future flood flows and may not be able to pass spring flow. As a result this road is damaged and will remain closed for the foreseeable future.

Kern County is taking the lead to develop a work plan for the short term to clear debris and sediment and improve the flow of water towards the existing bridge. But over the long run regular channel clearing is not the best environmental outcome and may not be the most economical solution.

An elevated causeway, or series of passages under the road, is a long-term solution that will increase capacity for future flood flows and prevent the river from washing out the road. This would also allow the river to flow naturally and wildlife to pass underneath.

Audubon is committed to working with Kern County and our neighbors to develop a solution based upon a cost benefit analysis, the best engineering approach, an understanding of floodplain geomorphology, damage to property and environmental concerns.

From the air on you can see how the new channel braids through pasture lands and then pools above Sierra Way Road.  The bridge and old channel are on hidden by the forest up against the hillside on the right. Prince Pond, South Fork Wildlife Area and Lake Isabella are seen below Sierra Way Road. 21 January 2011. Image courtesy Reed Tollefson.

Mary Whitfield surveys the newly discovered channel that cut across the former Colt Pasture during the December storm. 7 January 2011. Image courtesy John Stanek.

Looking upstream from the former Colt Pasture nature trail on 8 January 2011. Image courtesy Alison Sheehey.

You can see the westside of the Colt Pasture nature trail now completely cutoff on 8 January 2011. Image courtesy Alison Sheehey.

Looking downstream one can see the water levels remain high on 11 March 2011. Image courtesy Alison Sheehey.

The water made a clean cut across Colt Pasture nature trail road as seen on 8 January 2011. Image courtesy Alison Sheehey.

The river jumped its banks and sought out a low lying over-flow channel making it the new main channel. This now directs water to Sierra Way Road about 0.3 miles south of the bridge. 8 January 2011. Image courtesy Alison Sheehey.

The capacity for water to pass under Sierra Way Road is insufficient causing a large pool to form above it on the Hafenfeld Ranch and Kern River Preserve. This flooding is damaging to the road and reduces the value of the pasture to the rancher. 17 March 2011. Image courtesy Alison Sheehey.

A map of the new channel along with the existing channel that still carries some water but less than before the flood. Map by Sean Rowe © Audubon.

Information Resources for the Kern River Valley

North Fork Kern River data

South Fork River flow and stage - click event to get table of all data - click flow, stage to see chart

California mountain highway website. Local state highways - 178 and 155

CHP road website - select Bakersfield - click media information

Kern County road closures

Recollections from the Big Flood of 1966

Southern California flooding history


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