The new river course will be a low gradient channel, contain alternating riffles and pools every 75 to 100 feet. The bottom will be covered with clean gravel to give fish excellent spawning beds, according to Division biologist and stream restoration specialist Rod Van Velson.
The project is just the latest effort by the Division to maximize recreational fishing opportunities on public land. “The main objective of these projects is to improve the instream habitat for these fisheries,” said Greg Gerlich, Division aquatic biologist for the South Platte River. “By increasing habitat potential, particularly in a place like this where you have a trophy fishery, we hope larger fish will move up and find favorable habitat and remain here.”
But what makes this project unique is the plan to maintain optimum stream flows of between 8 cfs in the winter and 20 cubic feet per second (cfs) in the summer, creating spring creek conditions. In the summer, overflow from the main stream channel, which can run as high as 200 to 300 cfs, will be diverted into the habitat-improved channel. In the winter, water released from the reservoir will be directly diverted into the new channel. Water depth in the new channel will vary between 1 to 2 feet over the riffles, depending on flows, to 3-4 feet in the pools.
The old channel, which was straightened in the early 1900s to transport water downstream, has almost no trout habitat, Van Velson said. “The new stream channel, some of which follows the historic river course, will have tons of habitat,” he added.
The U.S. Fish and Wildlife Service provided funding for the project. The Denver Water Department helped with the design and will build a structure to divert water into the new channel. Over the winter, tree trunks, boulders and root wads to create structure and cover in the stream will be stockpiled for placement in the spring and summer.”
This is the second major stream rehabilitation project on the upper South Platte River that Van Velson and Gerlich have worked on in the past two years. In the fall of 1998, the pair guided the rehabilitation of a 1,000-yard stretch of the South Platte River below Spinney Reservoir, several miles downstream from Antero. Both projects used inmates from the Buena Vista Correctional Facility, who are learning to operate heavy equipment as part of their rehabilitation, to help defray construction costs. That stretch below Spinney now has a cobble stone riffle, rock vortex bars, root wads and stumps, tree trunks, j-hooks and pools. Point bars were shored up and planted with willows. Cut banks were stabilized and planted with native grasses.
The main thrust of the work below Spinney was to narrow the river and force fast water to the middle, where it won’t damage the banks. Clean water coming from the dam at Spinney has a tendency to pick up silt, eroding the banks and creating a wide, shallow river course, Gerlich said.
“We consider a stream to be stable when it is over a period of time naturally transporting its own sediment load without agrading or degrading the river. Since this system doesn’t have a natural sediment load, it’s not going to be able to build any point bars. It’ll continue to erode banks. So we’re coming in and trying to hydraulically fix it to what we think it should do based upon the normal flow regime of 38 cfs to 350 or 400 cfs.
Completion of the new project will conclude the second year of a $1 million, five-year stream rehabilitation project on the upper South Platte, according to Eddie Kochman, Division’s aquatic resource manager.
Kochman said the upper South Platte was a natural choice based on the amount of public land that borders the river, the popularity of the fishery, and the cooperation the Division has received from the Bureau of Land Management, U.S. Forest Service, the Colorado Department of Corrections, Park County and area landowners. “This is truly a cooperative project,” Kochman said.
Other planned projects include diverting flood flows in Three Mile Creek, which lies downstream from Spinney, through the flood plain instead of letting it dump sediment and debris into the South Platte. Violent, localized rainstorms have a tendency to flood Three Mile Creek, Gerlich said, which in turn trashes the South Platte River below its confluence with the creek.
The Three Mile Creek project needs to be completed before any improvements can be made downstream, Gerlich said. Kochman said the recent project is part of the learning curve as Division biologists refine their techniques and knowledge. “We’ve been doing stream restoration since the beginning of the agency,” he said. “But we have learned some things that we didn’t know before, and we’re using our experience to become more effective at what we do.”
Kochman credits VanVelson with much of the new approach. “He’s a real pro,” Kochman said. “He started out as a biologist, has become a hydrologist and even an engineer on these projects.”
The first 1,500 yards of the river below Spinney were restored in the early ‘90s, Van Velson said. But that treatment didn’t work as well as the Division had hoped. “Years ago, we’d put structure (like vortex rock bars) in, and we’d depend upon the structure to create a pool,” he said. “In lower gradient streams, it’s not going to happen.” He developed some of the new techniques on Grape Creek above DeWeese Reservoir in southern Colorado and on the Big Thompson River below Lake Estes a few years ago.
VanVelson said restoring a river to its natural condition is one of the highest goals an aquatics biologist can achieve. For Gerlich, too, this is about as good as it gets. “It’s probably some of the most rewarding work I do. I feel that I’m benefiting the natural resource, and I can actually evaluate and see the gains from my work,” he said. “And it’s extremely satisfying to be able to work with the inmates. You can see it in their faces that they feel good about themselves. They’re learning a valuable skill and that makes me feel good.”
It’s also beneficial from the economic point of view, Kochman said. A $50,000 to $60,000 project can be done for $30,000 to $40,000, utilizing the eight-man inmate crew to operate the heavy equipment. “Our partnership with the Department of Corrections has really leveraged our ability to do these jobs,” Kochman said.
Tom Bowen, Department of Corrections inmate project supervisor, said only inmates with the best records and highest chance to succeed in the “outside world” are chosen for the crew, which operates heavy equipment on a variety of public works projects for government agencies. “But I think they like this river rehabilitation work the best,” he said.