01/11/2024
Heart Butte Dam 2027 project will impact lake
by Luann Dart
The 75-year-old Heart Butte Dam is projected to undergo a modification project in 2027 which will significantly impact the levels of Lake Tschida for two to three years.
The earthen dam, which impounds the Heart River, was built in 1949 for flood control and irrigation purposes, but has also become a recreational gem.
Lake Tschida, which initially filled in 1950, is the reservoir created by the dam, with about 3,400 acres of water surface.
The U.S. Department of the Interior’s Bureau of Reclamation, which operates the Heart Butte Dam and the reservoir, has identified concerns regarding the potential for internal erosion, which could result in dam failure if left unchecked. So, the Bureau of Reclamation is planning a modification project at Heart Butte Dam, currently working through the design and permitting process.
Work on the dam will result in a lowering of Lake Tschida by about 30 feet, decreasing its size from 3,400 acres to 650 acres.
During an open house at the Lake Tschida Welcome Center Oct. 22, several entities were available to provide information about the project.
“We want to make sure we’re operating the dam safely, because that’s our No. 1 mission,” says Chris Langland, a natural resources specialist with Reclamation.
“We would like it to continue to function for another 100 years, really indefinitely,” Langland says. “It’s providing flood protection for the folks living below the Heart River and we still have irrigators that are seeing benefits of the dam and we have a great lake community here that loves the lake.”
Why is the
project needed?
The Bureau of Reclamation, which continually inspects the dam, found an issue about a decade ago.
During an inspection, sediment was found between one of the joints inside the outlet works conduit, indicating foundation material was moving and a void might be forming which could undermine the dam, Langland says.
That was immediately corrected with a filter system to hold the foundation material in place, which is basically a band-aid approach.
“It’s been stable since, so that’s the good news. The Heart Butte Dam is safe, but what is it going to take to make sure that it’s going to be safe for another 100 years?” he says.
Engineers have analyzed options and a project was identified. The modification project seeks to provide risk reduction by addressing potential internal erosion risks which have been identified through performance monitoring and extensive geologic exploration, according to the Bureau of Reclamation.
“It all gets back to the level of safety,” Langland says.
The proposed design includes conduit joint repair, a seepage cutoff system and a seepage blanket filtration system constructed at the downstream toe of the dam. Contractors will enter the conduit, which is the large pipe water flows through, and fill any voids with strong grout. Under that, they will build a cutoff wall down to the bedrock to strengthen the overall structure of the dam.
Because workers must enter the conduit, reduction of the water elevation is necessary to reduce the potential for uncontrolled spillway flow during the construction period.
“Our No. 1 priority is safety – safety for people doing the work, safety for people downstream in general, because we want to do it right,” Langland says.
What will happen
with water levels?
The outlet gate will be used to reduce the lake level from 2,064.5 feet to the minimum elevation in the summer of 2027.
By July 2027, the lake will be at the lowest level of 2,030 feet, so work can begin.
Water will be lower than anyone has seen it since the dam was built. Lake Tschida generally remains between 2,055 and 2,065 feet. The maximum was 2,086.23 feet April 9, 1952, and the minimum was 2,049 feet Oct. 25, 1991.
And the lake’s footprint will decrease from 3,400 acres to 650 acres. The majority of the reservoir west of Cabin Area 3 will be dry.
The lake will still be visible by the Welcome Center, but more dramatic differences will be on the western end of the lake, where the lake will be drier longer.
“There will still be a lake, just a lot smaller,” Langland says.
“It’s unique,” Langland says of the project. “We don’t typically drain dams in general.”
What are the impacts?
During construction, the downstream campground area will be closed as a staging area for contractors, but all other campsites will continue to be open. Lake campgrounds and day use areas will be open without lake access. Cabin owners will have no access to the water from lots during the maximum drawdown in the summer of 2027 and limited access in the summer of 2028.
“Obviously, the lake will be lower, so we can’t guarantee that boat ramps will be accessible,” Langland says.
Releases from Heart Butte Dam supply irrigation water to the Western Heart River Irrigation District, with approximately 13,100 acres of irrigable land. No water delivery will be available for irrigation in the summer of 2027, and will be limited in 2028.
The drawdown of Lake Tschida will have a temporary negative impact of the fishery, the Bureau of Reclamation states.
Fish are expected to go through the pipes as the lake is drained, while others will be isolated in the remaining water.
Those impacts are unknown, but the N.D. Game and Fish Department will restock the lake.
“We will do some pretty intensive stocking if we need to,” says Jeff Merchant, district fisheries biologist with the Game and Fish Department. “We don’t know at this point exactly what it’s going to do to the fishery.”
“It presents an interesting opportunity,” Langland says. “Because we’re going to be shaking things up, it has the opportunity to make for a better fishery on the back end.”
“It will be beneficial in the long run,” Merchant says.
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