Antero Reservoir project builds upon its history

Denver Water dam built in 1909 gets a major tuneup for the next century.

December 10, 2018 | By: Todd Hartman
People stand on a bridge looking at equipment that is part of the Antero Reservoir dam.
An inspection of the work done to upgrade Antero Dam, originally built in 1909.

 

Some 110 years ago, men using wagons, donkeys and sweat moved rocks, dirt and mud to build the dam at Antero Reservoir in South Park.

During the last few years, workers using excavators, dump trucks and 21st-century design reconstructed the dam, building on — and admiring — the labor of those who came before.

This fall, Denver Water formally certified the final phase of the five-year rehabilitation project as complete, ensuring this key reservoir — built in 1909 to feed the High Line Canal running through Denver — will safely hold water for decades to come.

“You’re up here outside of Fairplay and you think, ‘What does this have to do with Denver 100 years ago?’” said Doug Raitt, an engineering manager at Denver Water. “It’s really part of the great story about how forward thinking those people were who started these facilities, with the expectation that Denver and the Front Range would grow and need water to sustain that growth.

An excavator and heavy truck sits atop a dam with mountains in the distance.
The reconstruction of the dam at Antero Reservoir took advantage of the original design and benefited from modern-day excavators and other heavy equipment.

“So here we are really just maintaining what those folks did more than a century ago,” he said.

And indeed, workers built — quite literally — upon the efforts of their forebears, keeping the original configuration in place as they constructed a new, improved structure atop the existing foundation. The new dam — all 4,000-plus feet of it — is shorter, wider and stronger.

“We actually lowered the top of the dam and made both the upstream and downstream sides flatter, which increased stability and safety,” Raitt explained.

Antero Reservoir is the highest reservoir in the South Platte River system and gathers waters from the South Fork of the South Platte River, Salt Creek and other small tributaries. Its purpose has changed over the century, from a mid-season source of irrigation water for trees and crops in the Denver area to a reserve source of water that protects Denver Water customers in times of drought.

Reconstructing the dam required draining the reservoir. And prior to that, for safety reasons, it often held less than its full capacity of water.

Now, with the project complete and certified, the dam is holding back more water. Water levels are about two feet higher than they were before the project, said Casey Dick, a Denver Water engineer who managed design and construction at Antero.

Water pools in the foreground with snow-capped peaks in the distance.
The Buffalo Peaks and the Mosquito Range provide a magnificent backdrop at Antero Reservoir.

“It’s back up and running and we have every confidence in the facility and its ability to do its job for Denver Water,” he said.

Happiest of all may be anglers, for whom the reservoir is a star attraction in Park County.

The need to empty the reservoir and send the water downstream to other Denver Water facilities created a hardship for surrounding communities because fishermen went elsewhere, Raitt said.

“We realized when we were doing construction how important this resource was to Park County. It’s a statewide destination for fishing.”

When completed in 1909, the dam was state-of-the-art in dam technology, Raitt said.

Now, once again, the dam is up to contemporary standards. And it remains a crucial part of the water supply for a region still benefiting from the labor and ambition of our far-sighted predecessors.

A man guides the reins of two mules in a black and white photo. They're standing on the side of a ditch, with water running through the base.
The original dam at Antero Reservoir was the product of manual and animal labor — and a good sense of balance.

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