Repairs to Oak Creek water supply could cost up to $13M |

Repairs to Oak Creek water supply could cost up to $13M

The 67-year-old Sheriff Dam and Reservoir in Rio Blanco County has three issues that need to be addressed

Three different problems at the reservoir that serves as the town of Oak Creek’s water supply could cost up to $13 million to fix — roughly 25 times the amount of money the town spent on its entire water system in 2020.

Sheriff Dam and Reservoir is 67 years old, and fixing it is a top priority for Oak Creek. On Thursday evening, the town board was expected to approve a contract with water engineering company W.W. Wheeler & Associates, Inc. out of Englewood to better plan and understand the scope of the project.

“The biggest thing is going to be determining what the level of repairs are going to be, getting estimates for being able to make those repairs, timing it so we’re able to obtain financial assistance and then being able to bid it out and construct it in a mountain environment,” said David Torgler, town administrator for Oak Creek.

Engineers have been working with the town for over a year assessing the dam, Torgler said, but the project will still take a few years to get everything lined up.

Dana Miller, Division Six dam safety engineer for the Colorado Division of Water Resources, said there are three major components to the work. The first is to replace a gate and operator on the dam that is just old and has exceeded its design life.

Sheriff Dam is considered a high hazard dam, which is not a measurement of the quality of the structure, but of the values at risk if the dam were to fail. High hazard means that lives would be at risk, should the dam fail.

“It doesn’t have anything to do with the condition of the structure or the age of the structure,” Miller said. “Its just, if it were to fail, what would happen downstream.”

When it was built, there were not the same number of residents and other structures nearby. The emergency spillway, which allows water to flow around the dam in times of heavy rain and flooding, isn’t big enough for how it is now rated. The second part of the project is enlarging that spillway.

“It’s going to be a major upgrade for the town of Oak Creek; it’s going to be costly,” Miller said. “It doesn’t necessarily represent an immediate threat to the structure, but it causes an annual risk that’s unacceptable,”

The flood plane for the reservoir goes down Trout Creek into the Yampa River in Milner, Miller said. A larger spillway would ensure that if a large monsoonal rain storm were to drop several inches of rain quickly, the water would go around the dam and not over it, Miller said.

The third issue with the reservoir is a sinkhole that has developed while considering work on the spillway. Miller said they needed to take immediate action, essentially plugging the hole with clay, which temporarily mitigates the issue, allowing engineers to understand the extent of it better.

“We’re comfortable putting water in the reservoir each year and inspecting it and making sure everything is still OK, but we’re designing a more permanent solution to that issue,” Miller said.

Part of the work the town board plans to approve Thursday is an effort to better understand the cost of the repairs, which Torgler said has been estimated to range between $10 million and $13 million. In 2020, Oak Creek’s general fund budget was about 950,000, and the town spent another 470,000 on its water system from the dam to the water lines in town.

“It would be a big number for Steamboat,” Torgler said. “So that’s why we’re now doing the hydrology to narrow that number down to determine where we actually think what repairs are actually required.”

The next step is to find funding for the project. The contract on the agenda Thursday is just for $105,000 of work, but about 75% of it is being funded by grants from the Colorado Department of Local Affairs and the Colorado Water Conservation Board.

Torgler said this work is at the top of the town’s priority limit, and the town board has already said they are dedicating half of their roughly quarter-million dollars in pandemic relief aid from the American Rescue Plan to fixing the dam and reservoir. The other half is going toward broadband, he said.

The hope is to replace the outlet gate and operator stem next year, Miller said. Design for the spillway will also likely happen next year, with construction following in 2023 and 2024.

Torgler said they will need to partially drain the reservoir to complete repairs while also being able to provide water for Oak Creek. How far down they will have to drop the water level will depend on results of the engineering work.

“We won’t be emptying it,” Torgler said. “It’ll be lowered to a level where we can get in there and work on the dam safely.”

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