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Workers begin raising the dam at Gross Reservoir

Take an animated tour of the unique construction process.

Raising the height of a dam involves many steps, literally and figuratively. 

After two years of excavation and preparation work on the canyon around Gross Dam, workers in May began placing concrete, starting the three-year process of raising the height of the dam itself.

Denver Water is raising the height of Gross Dam by 131 feet as part of the Gross Reservoir Expansion Project. Once complete, the dam will be able to store nearly three times as much water in Gross Reservoir, which will add more resiliency and flexibility to Denver Water’s water storage system.

Workers from Denver Water and contractor Kiewit Barnard stand in front of Gross Dam in May to mark the start of the dam raise process. Photo credit: Denver Water.

Raising the dam is being done by building 118 steps made of roller-compacted concrete. Each step will be 4 feet wide with a 2-foot setback. The existing dam is 340 feet tall. The completed dam will be 471 feet tall. 

Check out this animated video to see how the process works.

The construction site at the bottom of Gross Dam with equipment used to place concrete and build the new steps. Photo credit: Denver Water.

It will take roughly three years to complete all the steps, with a final completion date set for 2027.

The dam raise process begins at the bottom of the dam using roller-compacted concrete to build the new steps that will go up the face of the dam. Photo credit: Denver Water.

Planning and permitting for the Gross Reservoir Expansion Project began in 2002. Take a look at this video to learn about the process and major accomplishments.