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CREEK AND WATERSHED STEWARDSHIP:
Creek-friendly Bank Protection |
 Back to Stewardship |
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| San Francisquito Creek and its tributaries support some of the most intact creekside, or riparian, habitat corridors on the Peninsula. Over time, however, increasing development throughout the watershed has exacerbated natural erosion processes. While many traditional efforts to stop erosion have altered flows and degraded habitat, new approaches to bank stabilization can protect both property and the creek. |
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Holistic approaches to bank stabilization
Holistic approaches to bank stabilization emphasize three main strategies. First, instead of focusing on a single problem or property, projects take into account conditions on an entire section or “reach” of creek that the project may influence or be influenced by. Cooperative projects among neighbors are often more successful than isolated projects because they address up- and downstream impacts.
Second, where possible, designs are based on restoring the size, shape, meanders, and other creek characteristics appropriate for the flow and velocity. Projects that use this approach will avoid compounding the problems causing the erosion.
Third, holistic approaches promote the use of native vegetation as a means to protect banks, known as “soil bio-engineering,” and limit hardscape techniques as much as possible. The roots of riparian vegetation provide long-term |
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stability by binding the soil, while the branches and leaves of the plants create “roughness” that slows down the flow and reduces erosive power. Vegetation on outside bends of meanders is especially important, as this is where flow velocities are highest.
Different sites require different treatments, and solution approaches can incorporate various vegetative, structural, and bank design components. Under urban conditions with space constraints, some hardscape features may be necessary to protect banks. But, even in these situations, the incorporation of vegetation into the bank treatments will improve both stability and habitat value. |
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Getting Started
Planning and undertaking a successful bank stabilization project requires the coordination of experts as well as review and approval from several local, state, and federal regulatory agencies.
Local permitting requirements vary by jurisdiction, and early consultation with planning staff of your city, town, or county will help you avoid spending time and money on a project that may not be permitted. The San Francisquito Creek Joint Powers Authority is also an excellent resource for questions about the planning process.
For complex projects, you should plan to involve technical consultants to assure the regulatory agencies (and your neighbors) that your project will minimize impacts to creekside habitat and will not negatively affect up- and downstream bank stability.
Some of the kinds of expertise that may be required include civil engineering, geomorphology, biology, and geotechnical engineering. Also, it is often more cost-effective and efficient to coordinate the permitting effort with the support of an experienced professional consultant. |
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Resources
Two excellent resources on bank stabilization were written for this watershed. While they focus on San Francisquito and Corte Madera Creeks, they contain conceptual restoration approaches that are generally applicable to the whole watershed. Both are available online and at the Acterra library (650-962-9876 x306).
The Streamside and Facility Protection Manual (in draft form at the time of press) was developed for the Santa Clara Valley Water Resources Protection Collaborative and provides guidance on bank protection and erosion repair. It is available from the Community Projects Review unit of the Santa Clara Valley Water District and when complete will also be available at the Acterra library.
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Bank Protection / Erosion Repair Design Guide.
www.valleywater.org (search for “Streamside and Facility Protection Manual”) |
In addition, you might find these general resources on soil bioengineering helpful.
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Restoring Streams in Cities: A Guide for Planners, Policymakers, and Citizens. Riley, A.L, 1998, Island Press.
Stream Corridor Restoration: Principles, Processes, and Practices. Federal Interagency Stream Restoration Working Group, 1998.
www.nrcs.usda.gov/technical/stream_restoration |
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