Arroyo de la Laguna Restoration Project
The Arroyo de la Laguna is the main tributary to Alameda Creek, the second largest drainage to the San Francisco Bay, with a total watershed encompassing approximately 700 square miles. The watershed is comprised of numerous land use sectors including protected parks and wildlife areas, private and public rangeland, urban development, suburban development and drinking water lands. Rapid suburban development in the upper watershed has caused severe instability in the lower 5 miles of the Arroyo de la Laguna. This has resulted in streambank erosion and channel widening of the Arroyo and increased sedimentation of Alameda Creek and the San Francisco Bay. This rapid erosion has adversely affected on-site wildlife habitat and continues to degrade upstream and downstream habitat particularly salmonid habitat in lower Alameda Creek. High sediment loads and the lack of vegetation present on the streambanks have severely modified the hydrologic function of this stream and have created adverse conditions for wildlife species that occur in the watershed.
In Fall 2006, the Conservation Partnership implemented a streambank stabilization project along a 1,000-foot section of creek between Pleasanton and Sunol, a half-mile south of the Verona Road Bridge. The project was designed to reduce streambank erosion, establish vegetation, and improve riparian habitat. The Arroyo is important habitat for the Western pond turtle, a CA species of special concern. The project was a successful collaboration with San Francisco Public Utilities Commission, Zone 7 Water Agency, Alameda County Public Works Agency, the Dublin San Ramon Services District, and Alameda County Water District on this $620,000 pilot project. Hanford ARC was the contractor for the project.
The site will be closely monitored over the next five years and will provide a demonstration of potential restoration and protective practices that can be utilized over similar stretches of the Arroyo. These efforts not only address the serious habitat issues both on-site and downstream but will lead to additional habitat restoration throughout the watershed as these demonstrated practices are applied watershed-wide.
2009 Project Update
Before the vegetation fully established, a few areas experienced unexpected erosion, including one of the Christmas Tree revetments, which was swept away in a 7,000 cubic feet per second storm event in January, 2008. As the site vegetation continues to establish these areas of erosion seem to be stabilizing somewhat. The vegetation has really taken off this year and there has been a lot of sediment deposition on the constructed terrace and along the edge of the terrace between barbs.
The vertical banks are continuing to slough after large storm events. However, the sloughing is minimal and is becoming part of the vegetated terrace instead of washing downstream, tending to reduce the slope of the banks. We believe the goal of letting the bank stabilize itself is being achieved. No additional trees from the top of bank have been lost since construction.
View photos from the project in our photo gallery.
More information on the full project and bioenginnering techniques implemented can be found below.
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