For the second summer in a row, crews have been hard at work at nearly 11,000 feet, trying to clear a caved-in tunnel that conveys water from Colorado’s Western Slope to Front Range cities.

The cities of Pueblo and Aurora have each spent about $4 million so far — $8 million total — on a project to clear and stabilize the Busk-Ivanhoe Tunnel, a remote, historic former railroad tunnel that remains an important part of the municipalities’ transmountain diversion system. 

The tunnel was originally built for the Colorado Midland Railroad in 1891, which connected Leadville with Aspen and Glenwood Springs over the Continental Divide, before it became a toll route for automobile traffic from 1922 to 1943, according to a history provided by water managers. Its use as a transmountain diversion also dates to the 1920s.  In recent decades, it has served primarily as an aqueduct that takes water from Ivanhoe Lake to Busk Creek and into Turquoise Reservoir, where it’s stored until it can be used by residents in Aurora and Pueblo. The two cities own roughly equal shares of the water.

According to Alan Ward, water resources manager for Pueblo Water, officials knew the tunnel had been gradually deteriorating, but about two years ago they started to see a noticeable decline in the flow rate. That’s when workers realized there had been a major collapse that crushed the pipe carrying water through the two-mile-long tunnel about 500 feet inside the west portal.

“We were still running a decent quantity of water through the pipe, but that started to change to the point where we were struggling to get our full water entitlement through it,” Ward said. “We had seen a consistent decline over several years and we decided this is a problem that’s not going to clear itself out.”

During the summers of 2022 and 2023, crews from the company Drill Tech have been clearing out the tunnel — mounds of rocky debris and rotten timbers are piled outside and hauled away regularly — and shoring up the roof and sides. Workers live on-site all summer in two cabins, tents and campers. 

“This isn’t the type of project where employees are going to commute in each day,” Ward said. “You’ve got that cost that goes with maintaining a spot for them to stay and you have to pay to convince people it’s worth it to be gone from their families for weeks at a time. It’s a big sacrifice to do that kind of construction work.”

This photo shows the inside of the west portal of the Busk-Ivanhoe Tunnel, part of a system that conveys water from the headwaters of the Fryingpan River to the cities of Aurora and Pueblo. A cave-in in the 132-year-old tunnel has damaged the pipe and restricted the amount of water that can flow through it. Credit: Heather Sackett/Aspen Journalism

Transmountain challenges

Remote locations, long winters and aging infrastructure with expensive fixes are all challenges cities face with carrying water from the headwaters of the Colorado River basin to the Front Range. Today there are 24 transmountain diversions (TMDs) that move water from the Western Slope across the Continental Divide to the eastern part of the state, taking roughly a combined 500,000 acre-feet a year. These TMDs were constructed to solve a simple yet crucial problem: Most of Colorado’s water is on the Western Slope, but most of the state’s population lives on the eastern side of the divide. 

Some of these complex systems of buckets, tunnels and canals convey a large percentage of the water supply for Front Range cities. For example, Aurora uses four TMDs from the Colorado River basin, from which the city gets about 25% of its water. 

The two cities can take on average about 5,000 acre-feet per year through Busk-Ivanhoe system — roughly 2,500 acre-feet each. This amount is small compared to other sources; it’s only about 4% of Pueblo’s supply and 2.4% of Aurora’s, according to water managers. Still, in a hotter and drier climate with looming shortages, it’s important enough for cities to spend time, money and resources securing even these small sources of water.

“It’s as simple as: Water is so precious and valuable in this part of the country that even if it’s only 4% of your yield, you can’t really afford to just walk away from it,” Ward said. 

The Busk-Ivanhoe collection system works by funneling water from surrounding tributaries — Ivanhoe, Lyle, Hidden Lake and Pan creeks — via ditches, into Ivanhoe Lake, which can hold about 850 acre-feet and acts as a forebay before the water is sent through the tunnel. 

Ivanhoe Lake, at the headwaters of the Fryingpan River, is a natural lake that also collects water from the surrounding drainages to be held temporarily before being sent through the Busk-Ivanhoe Tunnel to Turquoise Lake. Because crews are currently working on the tunnel, water is now sent down Ivanhoe Creek and picked up by the infrastructure of the Fryingpan-Arkansas project and sent to the same destination: Turquoise Lake. Credit: Heather Sackett/Aspen Journalism

But since the tunnel is currently under construction, the cities are using infrastructure from the Fryingpan-Arkansas project through an agreement with the Bureau of Reclamation to get the water to the same destination: Turquoise Reservoir and the Arkansas River basin. 

Water can be sent from Ivanhoe Reservoir downstream via Ivanhoe Creek and picked up by the Fry-Ark’s Nast Tunnel and then the Boustead Tunnel, which conveys water under the divide into Turquoise Reservoir. 

“We don’t normally use that when the tunnel is working like it should, but when we are doing construction or repairs, it’s a backup for us,” said Rick Kienitz, a water resource manager with Aurora who manages the city’s Colorado River basin source. “We can only do that when (the Fry-Ark system) has capacity.”

The Busk-Ivanhoe tunnel isn’t the only alpine transmountain diversion currently in need of extensive repairs. Grizzly Reservoir, an alpine lake above Aspen and part of the Twin Lakes Reservoir and Canal Co.’s system, was slated to be drained this summer so its dam and outlet works could be repaired. The company plans to install a membrane over the steel face of the dam, which was constructed in 1932 and is corroded and thinning.

That rehabilitation project, which was estimated to cost $7 million, has been pushed to summer 2024. Pueblo, Aurora and Colorado Springs own 95% of the shares of Twin Lakes water. Ward is also on the board of Twin Lakes.

“We have the same challenge with the remote location,” he said. “It’s difficult to get big equipment up there to do the work.”

Officials say this summer’s work on the Busk-Ivanhoe tunnel is going well, although it may take years to repair the entire length. Crews have made it through one of the largest sections of the cave-in, but there are still blockages ahead and they expect more work will be needed next season. 

Ideally, the whole tunnel would be cleared and stabilized so that a work vehicle could drive through, much the same as at Grizzly Reservoir, where caretakers are able to drive through the four-mile-long tunnel to reach Highway 82 on the east side of Independence Pass. The only way to access the Busk-Ivanhoe infrastructure currently is to drive an hour from Basalt up Fryingpan Road or over Hagerman Pass when it opens in mid-summer.

A cave-in about 500 feet inside the west portal of the Busk-Ivanhoe tunnel severely restricted the amount of water that was able to go through it. The tunnel takes water from the headwaters of the Fryingpan River, across the Continental Divide, for use by the cities of Aurora and Pueblo. Credit: Heather Sackett/Aspen Journalism

“We have two guys who are caretakers up there from April to October and if they could have access through that tunnel all the way to the other side, it would give them another way to get out,” Kienitz said.

Water managers are taking the tunnel project year by year and haven’t yet decided if they will tackle the entire two miles. Crews will keep chipping away until mid-October when snow chases them out of the high country. At that point, water managers will turn the diversion back on to see how much water is able to flow through after two summers’ worth of work.

“We are going to test it at the end of the year to see what kind of improvement it may have made,” Kienitz said.

Heather Sackett is the managing editor at Aspen Journalism and the editor and reporter on the Water Desk. She has also reported for The Denver Post and the Telluride Daily Planet. Heather has a master’s...