Net installation begins at Elkhead Reservoir
September 23, 2016
Dressed in rain slickers reminiscent of the Gorton's fisherman, the crew installing a $1.3 million net across the spillway at Elkhead Reservoir took to the water Friday morning.
Although the wet, cold and windy conditions didn't prevent Dave Erickson, owner of Pacific Netting Products, and his team from positioning the net across the spillway, it won't be anchored to the bottom until later on.
"(Friday) we probably won't deploy it down to the bottom but we'll get it all tied in place," Erickson said. "It's going to take a little bit of time."
The net install is part of the Upper Colorado River Endangered Fish Recovery Program's effort to keep nonnative northern pike and smallmouth bass from spilling out of the reservoir into the Yampa River where they prey on four native fish — the humpback chub, bonytail, Colorado pikeminnow and razorback sucker.
Tom Chart, recovery program director, said after studying the level of escapement of fish through the spillway, it became apparent that issue needed to be addressed.
"It was probably twice as much as we thought we could handle out there in the river," he said.
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The original thought was to use rotenone to chemically poison the fish in the reservoir, but that option turned out to be unfeasible and unpopular with locals.
As an alternative, the recovery program began to discuss the idea of a net with other stakeholders and eventually the project was funded through $500,000 from Colorado's Native Species Conservation Fund and about $800,000 from the recovery program.
Erickson said the is net approximately 575-feet long and extends to a depth of about 30 feet.
"It's a full-exclusionary net so it goes from bottom to surface," he said.
The net is fabricated from a sturdy polyethylene filament called Dyneema manufactured in the Netherlands and an Italian company weaves the Dyneema into a knotless mesh at their plant in Slovakia. It will be secured to the bottom via anchors that were put in place when the reservoir was expanded in 2006.
In front of the net, a 24-inch diameter, 800-foot long, foam-filled debris boom with a 4-foot skirt that extends below the surface will protect the net from logs and other flotsam.
"It stops wave action from down below and then it also acts as a debris deflector," Erickson said.
Boom installation will begin on Monday.
Ray Tenney, deputy chief engineer with the Colorado River Water Conservation District, said that water flow inevitably overwhelms the 575-cubic-feet-per-second capacity of the screened outlet towers year after year.
"We knew going into enlarging Elkhead that there would be a frequency that we wouldn't be able to contain — we just didn't know it would be as much as it is," he said.
In 2016, the spillway was active for 24 days.
The new net will remain effective up to 2,000-cfs through the spillway, Tenney said.
"If we had the flood that this is designed for, there'd be 14 feet of water over the spillway and the valley would be all flooded below," he said.
CPW's Chief Aquatic Biologist Lori Martin said native species are often used to gauge the overall health of an ecosystem.
"When you start losing those species, something is not right," she said.
And although CPW wants to preserve the fish as a part of the recovery program, striking a balance with local anglers is just as important.
"This is a perfect way to be able to do that," she said. "Putting the screen in allows us to be able to manage Elkhead for fish that are considered compatible for native species recovery."
As part of its effort to transition the fishery away from smallmouth and northern pike, CPW plans to stocke approximately 20,000 largemouth bass in the reservoir over the summer with the help of local anglers like Burt Clements.
"Four or so of us came out with boats and we distributed largemouth around the lake," Clements said.
Chart said one of the most important things the recovery program does is provide a buffer between the federal government and regional water users.
"The program is the endangered species act compliance for all the water development that happens through the upper Colorado River system," he said. "We are working with water users hand-in-hand and there's a lot of people who want a successful program — it's not just fish biologists. It's the water users as well."
For more information on the Upper Colorado River Endangered Fish Recovery Program, visit http://www.coloradoriverrecovery.org/
Contact Patrick Kelly at 970-875-1795 or Contact Patrick Kelly at 970-875-1795 or pkelly@CraigDailyPress.com or follow him on Twitter @M_PKelly.Contact Patrick Kelly at 970-875-1795 or pkelly@CraigDailyPress.com or follow him on Twitter @M_PKelly.