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Napa County Resource Conservation District |
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Napa County Resource Conservation District |
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In 1999, the Napa RCD completed two demonstration stream restorations sites through a grant from CALFED. The purpose of the restoration sites was to demonstrate spawning habitat and stream restoration using natural processes. The two projects demonstrated the use of vortex boulder weirs and willow revetments. Vortex boulder weirs are intended to:
- Provide instream cover and deepen feeding areas in riffle habitats.
- Provide a wide range of velocities for salmonid holding water at high flow without creating backwater or sediment deposition
- Act as a grade control structure without upstream lateral migration, bank erosion or aggradation, characteristic of some log or boulder weir designs
- Maintain a low width/depth ration to reduce sediment deposition and maintain the sediment transport capacity of the channel.
Willow revetments are intended to enhance bank stabilization and restrict sediment yield to a stream and also provide vegetation and canopy.
These demonstration sites were good examples of collaborators in the watershed who had a goal in mind. The Guidance Committee for this project was a compilation of many different local agencies, interest groups and landowners who
Boulder Vortex Weir on Sulphur Creek- Before and AfterThe demonstration sites chosen were good examples of collaboration in the watershed, people working together with a goal in mind. The Guidance Committee for this project was a compilation of many different local agencies, interest groups and landowners including: Department of Fish and Game, Pierce's Disease Task Force, Napa Sustainable Wine Growers, Flood Control and Water Conservation District, Napa County Land Trust, Friends of the Napa River, Napa Valley Grape Growers Association, Natural Resources Conservation Service, Napa-Sonoma Mosquito Abatement District, Napa County Farm Bureau, Region II Water Quality Control Board, Agricultural Commissioner, Carneros Quality Alliance, Bacchus Agriculture Services and Watershed Stewardship Groups.
Cooperators Make Stream Restoration Happen!!!
Stream Restoration With Weir Installation
BEFORE: Overview of restoration site looking downstream from footbridge.
AFTER: Looking downstream from footbridge. "Yellow" banks (right, foreground and leftbank in distance) have been sloped back, seeded with native grasses, covered in erosion control blanket and planted with native shrubs. The pool in the left foreground is just below the upstream vortex boulder weir. Middle weir is just downstream, next to "yellow" section of leftbank.
AFTER: Same restoration site during first year flows.
Stream Bank Restoration On Sulphur Creek
BEFORE: The left bank is severely eroded at this site. The alder tree on the right is leaning across the creek, due to the undermining of its roots. Many alders along this reach have exposed roots, like this one. Many other have buried roots and trunks, indicating huge fluctuations in sediment load.
AFTER: The vortex weir, shown in the right foreground slopes up, behind the eroding alder roots, in an attempt to protect this tree. The "blue" rocks that are visible next to the alder roots indicate the top of the toe rocks placed along the bank (toe rocks are no long visible). The bank was stabilized with sloping, planting and erosion control blanket. Also, note the pool (calm water) just downstream of the weir.
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