Flowing from the Santa Ynez Mountains, San Roque Creek, in Santa Barbara, flows south before eventually discharging into the Pacific Ocean at Arroyo Burro beach.  At the foothills of the mountains along San Roque Creek lies Santa Barbara County Flood Control District's San Roque Debris Basin.  The purpose of this facility is to capture sediment and debris during high flow events to protect downstream infrastructure from flooding damage. In the decades preceding the project, the constructed facility consisted of an eartherned dam, encapsulated in concrete, with an undersized, 36 inch culvert running through the base of the dam.  

 

Through many storm events, the facility performed its intended purpose, however, because of the culvert running through the dam was undersized, it often plugged with debris and lacked the ability to carry water and smaller sediments downstream. Because entrapped smaller, sand size, sediment remained in the debris basin after storm flows, its accumulation reduced basin capacity for future debris capture and added high maintenance cost for the County to continually remove sediment that posed no threat to infrastructure from the basin. Eventually, in 2026, the culvert through the dam failed, which enabled the County to pursue the rehabilitation of the facility with a more modernized approach.

​

That modernized approach consisted of removing the center part of the dam, reinforcing the sides of the dam with grouted rock slope protection, installing a debris rack, and reconstructing approximately 500 linear feet of new stream channel to allow for the more natural sediment transport, promote fish passage for endangered Southern Steelhead Trout, all the while retaining the intended purpose of flood protection.  With the modification of the dam, smaller/finer sediments are now able to be washed downstream, while bigger more potentially destructive sized boulders will be caught behind the dam, thus protecting downstream infrastructure.  The project serves a multiple benefits from enhancing habitat access for wildlife, reducing of costly maintenance, and providing more effective flood control.

​

River Reach Environmental had the pleasure to act as the technical consultant directing Granite Construction on how to rebuild the stream channel correctly, advise on project dewatering activities, and act as the biological monitor.  Being a time and materials project, it allowed Flood Control and River Reach Environmental to make on the fly field decisions to ensure the project was built robust and performs as intended into the future.​​