Reclamation and Restoration Professional Practice Network
Bioengineering and Stream Rehabilitation at Dublin Ranch
by Matt Quinn
Over the past 10 years H.T. Harvey & Associates has been involved in the restoration and conservation of hundreds of acres of land in the Dublin, California area. Due, in part, to decades of unmanaged grazing, many of the creeks in this area are highly degraded, unstable, incised channels. The environmental setting provides a great opportunity to integrate bioengineering techniques into ecological restoration and rehabilitation designs for these degraded stream corridors.

In 2003, a reach of Tassajara Creek was identified as an ideal location to increase the riparian habitat quality, specifically for the existing population of the federally-listed California Red-legged Frog (Rana aurora draytonii), as well as to provide erosion control and bank stabilization in an area prone to bank failures. H.T. Harvey & Associates and Clearwater Hydrology collaborated on the design and construction of an approximately 180-foot long reach of Tassajara Creek (see Figure 1 for a typical cross section of the site.)

In 2004 construction was completed. Streambank structures included rootwad and log structures keyed,
Cross section drawing

                     photo courtesy H.T. Harvey & Associates 

Figure 1. Cross section drawing of the proposed Dublin Creek restoration site

and in some cases cabled, into the bank (see Photos 1 and 2). These structures were designed to provide escape cover, and resting and foraging habitat, for the California Red-legged Frog, as well as to improve the stability of the Tassajara Creek streambank. Numerous willow stakes were interplanted within these streambank structures to provide an additional measure of erosion control and improve the quality of the shaded, aquatic riverine habitat. Photos 3 and 4 were taken after the site had been through two winter seasons, both of which produced numerous short duration, high velocity flows.

Preparing the site

Photo 1. Preparing the site for
placement of rootwad and log
structures

Finish grading

Photo 2. Finish grading following
placement of wood and
rock streambank structures

photos courtesy H.T. Harvey & Associates 

Section of finished

Photo 3. Section of finished
streambank looking downstream.

Section of finished-2

Photo 4. Section of finished
streambank looking upstream.

photos courtesy H.T. Harvey & Associates 


At the time this article was written (spring 2006) the vegetation planted within the site was continuing to establish and the rootwad and log structures were functioning as designed. Of particular interest, focused surveys for wildlife usage confirmed that the local population of California Red-legged Frog was using these rootwad and log structures.

This project is a good example of how bioengineering techniques can be integrated into ecological restoration and rehabilitation designs to provide benefits such as wildlife habitat, erosion control, and streambank stabilization.

Matt Quinn works for the ecological consulting firm H. T. Harvey & Associates as an ecologist. He can be reached at mquinn@harveyecology.com. Lee R. Skabelund, ASLA, of Kansas State University, serves as co-chair of the Reclamation & Restoration PPN.
 
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Lee Skabelund, ASLA, Chair
(785) 532-2431  
lskab@k-state.edu