Fish habitat improvement and flood control projects on two Fortuna creeks are almost complete, after a busy summer of activities that at times restricted traffic on both 12th Street and South Fortuna Boulevard.
The fish passage improvement project on Rohner Creek included numerous improvements to the culvert and stream channel at 12th Street.
“The project includes a combination of concrete weirs on the outlet apron (of the culvert), and a step-pool roughened channel downstream of the crossing structure,” GHD civil engineer Brett Vivyan said.
Four concrete weirs span the 10-foot channel width on what is called the culvert apron, providing pools and small water surface drops that are conducive to fish passage. Downstream improvements include the installation of nine channel-spanning rock weirs and rock-lined pools.
Vivyan said the project at 12th Street has other benefits as well.
“Flood control improvements were also implemented with the construction of a low berm and flap gates on the storm drain outlets,” he said.
Vivyan said the stream channel banks at this location were seeded with a native riparian plant mix and a biodegradable mat was installed for erosion control.
In-stream work began on June 17 and the last day of work was October 15. This project is funded by the California Department of Fish and Wildlife Fisheries Restoration Grant Program, through a more than $700,000 grant awarded to the city of Fortuna in March; McCullough Construction Inc is the contractor.
The Hillside and Rohner Creeks minor flood control improvement project included the replacement of three culverts and the restoration of 1,500 feet of Hillside Creek between Rohnerville Road and Fortuna Boulevard. The new culverts are on Hillside Creek, near the confluence with Rohner Creek, at the Cal Fire building on South Fortuna Boulevard, under the access road to Four Star Mini Storage and between Les Schwab and the apartment complex closer to Rohnerville Road built near the creek. Vivyan said the culverts are filled with a two-foot thick section of various sizes of rock to emulate a more natural stream bed, providing flow variation for fish passage.
“The upper half of the channel (of Hillside Creek) was restored to a more natural creek channel with a meandering channel and alcoves with log habitat structures,” he said.
He said approximately 700 feet of upstream was restored, and the banks were seeded with a native riparian and wetland plant mix and biodegradable mat was installed for erosion control. The wider and deeper channel should reduce flooding in this area. Work on this project also began on June 17th and Glissman Excavating was the contractor doing the work on this $1.7 million dollar project, funded by the FEMA Hazard Mitigation Grant Program and City of Fortuna Measure E funds.
Vivyan said additional planting and landscaping activities are planned for both the 12th Street and Hillside/Rohner Creek fish habitat and flood improvement projects. Native riparian planting will take place in both locations now through the end of the year. For the upper reaches of Hillside Creek, planting will occur after rains have saturated the upper level of soil. Native plants will include Common rush, Hedge Nettle, Tufted Hairgrass, Slough Sedge, California Blackberry, Wax Myrtle, Coast Twinberry, Western Thimbleberry, Salmonberry, Redosier Dogwood, Black Cottonwood, Pacific Willow, and Red Alder.
"fish" - Google News
October 29, 2019 at 02:56AM
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Fish passage improvements made on Rohner Creek - Eureka Times-Standard
"fish" - Google News
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