GRANITE — The Arkansas river both ambles and rages below Leadville, with gold-medal fishing, Class II to Class V rapids hosting hundreds of thousands of rafting trips and a vast, aging network of reservoirs and pipelines that water two of the biggest — and thirstiest — cities in the state.
But just below the former riverside mining camp of Granite, where a dilapidated dam built in 1964 has long blemished the Arkansas River’s beauty, rebar jutted from concrete blocks, preventing raft passage and spawning trout battled the steep wall of blasted rocks to reach upstream pools.
“Not a lot of thought went into recreation or fish when this dam was built,” said Ronald Sanchez, an engineer with Colorado Springs Utilities.
A lot of thought is going into fish and recreation now, as water managers in Colorado Springs and Aurora join the Colorado Water Conservation Board, the Pueblo Board of Water Works, Colorado Parks and Wildlife and the Arkansas Headwaters Recreation Area in rebuilding the diversion that directs water to the Front Range.
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The $9.1 million project will make the entire river from Leadville to Cañon City navigable for rafts for the first time in at least 55 years.
It’s part of the vast Colorado Springs- and Aurora-owned Homestake Project that brings Eagle River Basin water from the Holy Cross Wilderness to the Arkansas River Basin, through the Homestake, Turquoise and Twin Lakes reservoirs for delivery to the Front Range cities.
The cities started construction of the Arkansas River diversion in July 2018, creating three distinct channels below a rebuilt intake that serves as a backup water diversion to the Otero Pump station downstream of Twin Lakes Dam. Before the Twin Lakes Dam was built in the late 1970s, the diversion was the original intake that collected and directed water to the Otero Pump station for delivery to Aurora and Colorado Springs.
One channel is a fish ladder for spawning brown and rainbow trout. Another channel is a spillway to accommodate flood-level flows like the ones that swelled the Arkansas River this spring. And a third is a series of six drops allowing rafts safe passage.
The project marks a new era of collaboration between the diverse interests on the Arkansas River between Leadville and Cañon City, one of the most recreated stretches of river in the U.S.
“For me the coolest thing about it is that you have these large water utilities in Colorado going above and beyond to do the right thing for the next 50 years,” said Salida-based whitewater park engineer Mike Harvey.
Ten years ago, Harvey helped the Arkansas Headwaters Recreation Area craft a report urging Aurora and Colorado Springs to consider recreation and fish when it came time to rebuild the Granite Dam diversion.
“Hopefully this is the precedent that will be followed all over the state,” he said. “It kind of feels like it is. It doesn’t feel like we have to convince the classic water buffalo types that they have to think about boating and fish anymore. They seem to largely be on board these days.”
Harvey, who has designed dozens of whitewater parks for Boulder’s pioneering design firm Recreation Engineering & Planning, including parks on the Arkansas River in Salida and Buena Vista, helped plan the boat chutes for the Homestake project. Deere and Ault Consulting led the design, building a scale replica of the channels and floating miniature rafts and kayaks through the model to make sure the computerized engineering was on-point.
“There were some final tweaks we had to do after seeing the scale model,” said Sanchez, standing atop the walls separating the channels as crews assembled a huge pipeline for the submerged, concrete intake structure, which the engineering team pushed further into the current after testing the scale replica. “By tweaking that in the model we felt much more comfortable with the design we were going with. That’s not something we could have done in the field.”
The Arkansas River accounts for more than $74 million of the $177 million in economic impact created by commercial rafting in Colorado. The 102 miles of river in the Upper Arkansas River Valley also ranks among the 322 miles of Colorado waterways that qualify as Gold Medal Fisheries that can yield a dozen large trout per acre. It also supplies a large percentage of water to Colorado Springs and Aurora via the 66-inch pipeline that runs from the Otero Pump Station.
Rebecca Mitchell, the executive director of the Colorado Water Conservation Board, said the project exemplifies the collaboration of the Colorado Water Plan, which gathered perspectives from all types of water users in the state to create a policy roadmap for future water planning across the state.
Colorado Parks and Wildlife and the conservation board provided $1.2 million in funding through Colorado Water Plan grant programs.
“This is the type of win-win project envisioned by the Colorado Water Plan and a good example for future projects that the CWCB would like to continue funding,” Mitchell said in an email.
Aurora and Colorado Springs partnered on the Homestake Project in 1958 and started planning an upgrade for the diversion below Granite more than a decade ago. The new intake system is a backup in the event the federal government ever needs to work on Twin Lakes and the supply to the Otero Pump Station is disrupted.
It also can help the two cities take better advantage of their water rights during high-flow years, when Homestake, Turquoise and Twin Lakes reservoirs are full and spilling excess water into the Arkansas River. The intake at the new diversion allows the cities to capture that water and divert it to storage facilities on the Front Range.
“Under certain storage and flow conditions, we can actually increase our yield,” Sanchez said.
Both cities have an agreement to keep recreational flows in the Arkansas River during the summer rafting season. The agreement also keeps year-round flows in the river that support a healthy fish population. The construction of the boat chute and fish ladder are “a natural extension” of that flow-management program, Sanchez said.
“Our primary responsibility is to take care of our assets and assure our water deliveries, but we saw this as an opportunity to collaborate with our major stakeholders,” Sanchez said.
The cities have left the old dam’s stone pillars intact and will install historical signage along the former Denver Rio Grande railway. Project engineers saved concrete slabs from the old structure to pave a portage path around the diversion. The project engineers also used plenty of river boulders in the channels as well, grouting each stone in place to ensure stability as well as smooth, rolling water.
“Even though it is a big structure … it looks somewhat natural versus being a bunch of poured concrete everywhere, which is what they could have done,” said Rob White, the manager of the Arkansas Headwaters Recreation Area. “Colorado Springs and Aurora really stepped up the engineering on this project and really in the whole process they used in their design. It definitely sets a new standard for what I consider the way we should move in the future.”