There have been a number of California State Parks (CSP) streambank stabilization treatments applied over the years to the banks of the Upper Truckee River through the golf course to help reduce bank erosion and minimize the fine particle sediment delivered to the river as well as to protect infrastructure. These projects were installed as a temporary solution, or as “spot treatments” to a much larger problem.
Prior to CSP purchase many eroding banks were treated with boulder rip rap, but much of that has failed. Also this treatment is usually done under bridges to help protect the banks during high flow events because the width and movement of the river is restricted.
In 1992 approximately six sites were treated with root wad bank structures to help slow the velocity and decrease the erosive force of the water, while protecting the bank from the direct flow of the water. Root wad treatments were applied to the outside banks of bends in the river. The bank is excavated and a large tree root wad is placed in the bank, anchored and re-covered, leaving the ball of the root mass exposed and angled to deflect the flow. Unfortunately, many of these structures fail because the water eventually finds a weak spot usually at the upstream or downstream end of the treatment and erodes behind the root mass leaving a gapping hole in the bank.
A large log brush box was installed at a site that has had substantial bank erosion over the years. This site is just downstream from an undersized bridge (hole 6), which accelerates flow downstream, contributing to over 40 feet of bank erosion in the last 10 years, and dumping abundant fine sediment into the river. The brush box was constructed with beetle-killed whole lodge pole pine trees and 10 inch diameter steel pilings driven into the bed. The length of the brushbox in total was over 300 feet long and 10-12 feet high. The structure was tied into the bridge and the next downstream point bar, and serves to reduce flow velocities and deflect flow away from the bank.
Although these project help to reduce bank erosion, they are temporary spot treatments and do not fix the overall problem or restore habitat.
Bank Stabilization in Pictures
Here are photographs of the various bank stabilization projects:
Severe erosion has occurred downstream from the hole 6 bridge where first a rip rap treatment, then a previous old brush box failed.
New brush box was installed in 2005 at the site downstream from the hole 6 bridge.
Root wad bank treatment protects bank but immediately adjacent bank erosion is increased.
Log structure just upstream of the hole 7 bridge. Erosion behind the structure continues, but at a slower rate.
Failing rock rip rap structure along hole 18