In the 2000s, staff at the Colorado River District raised alarm bells that the Ritschard Dam — which was constructed in the mid-1990s to impound Wolford Mountain Reservoir outside of Kremmling — was moving and settling.

In the worst-case scenario, the dam could crack, then ultimately fail, sending 66,000 acre-feet of water rushing down to Kremmling. Although the scenario was unlikely, experts consistently monitored the dam over the next 20 years.

At the March 4 Grand County Board of Commissioners meeting, the Colorado River District shared good news: the dam’s settling was no longer cause for alarm.

At the meeting, river district staff presented its 2024 Comprehensive Dam Safety Evaluation, which showed the likelihood of Ritschard Dam’s failure is “within industry-accepted tolerable risk guidelines.” This means that although there’s always a risk of failure for any dam, there is no need to rehabilitate or repair the dam.

Andy Mueller, the river district’s general manager, told commissioners that the district has partnered with “experts from around the world” to complete the evaluation and is confident in its results.  

Dam failures can result in property damage or loss of life. For this reason, numerous evaluations have been needed, along with discussions with the county’s office of emergency management.

“Public safety will always remain at the top of our list,” Mueller explained. “That’s why we’ve frankly spent millions of dollars examining this dam and making sure we understand what’s going on.”

History of monitoring the dam

The Ritschard Dam is owned and operated by the Colorado River District. D.H. Blattner and Sons of Minnesota constructed the 122-foot-tall dam between 1993 and 1995. It is composed of a clay core, covered by rockfill with a sand filter.

According to the river district, the clay core provides a barrier that prevents water from passing through the dam. If the settling were to cause cracks in the core, water could enter and eventually lead to the dam’s failure if nothing was done.

Since construction, the dam has shifted down 2.6 feet. The top of the dam has also moved sideways about 8 inches. This is possibly due to poor rockfill compaction. However, the district hasn’t pinned down an exact reason for the settling.

Hunter Causey, the district’s director of asset management and chief engineer, told commissioners that he and other staff members “have been keeping a really close eye” on the dam. Contractors have added additional feet to the top of the dam because of the settling.

After using monitoring devices to study the dam every day, the river district conducted comprehensive safety evaluations in 2016 and 2020. The 2020 evaluation found that risk had increased.

“The estimated risk was high enough to justify us taking action to better understand that risk and try to reduce that risk,” he said.

Beginning in 2021, the district ramped up its study of the dam, including lab testing, on-the-ground surveys, lidar scanning and more. Then in 2024, the district conducted its latest evaluation.

“We hired three of arguably the best geotechnical engineers in the world to come look at this with us,” Causey said. “We had our consultants, staff, stakeholders, and we hired a facilitator to be kind of a neutral party to guide the process.”

Once these experts convened, it was time to put all their findings into the evaluation. Causey said the team had two significant findings:

• First, “laboratory testing of samples of the clay core determined that the clay is extremely resistant to erosion,” according to the district. Causey explained that in the lab, technicians drilled holes in samples of the core and applied pressurized water to test erosion susceptibility.
• Second, testing was done on samples of the dam’s filter, which staff had previously feared might not be up to par. The dam’s filter, located directly downstream of the core, is designed to catch any potential eroded material.

“It acts as a self-healing mechanism, so if you ever have eroding of that clay core, that filter actually clogs up and seals those leaks if they do form,” Causey said.

Fortunately, lab testing found that the filter could do its job. Overall, the 2024 evaluation was a significant improvement over the 2020 evaluation. Causey explained that there were a lot of uncertainties in 2020 and that new findings answered a lot of those questions in 2024.

In addition, the settling has abated in recent years, although it is expected to continue at a slower pace.

The future of Ritschard Dam

Causey said the latest evaluation “brought welcome news” to the district and ultimately the residents of Grand County and the Front Range.

Denver Water leases water from Wolford Mountain Reservoir for Front Range communities. Western Slope communities also use this water. And the reservoir is a favorite spot for people to boat, fish and camp. Since there is currently no need to repair the dam, communities will continue to benefit from it for decades to come.

Causey said staff will continue to monitor the area, as it has been doing. In addition to this vigilance, staff will work with the county to develop an emergency preparedness plan for any possible dam breach or leaks. Any future evaluation would be on an as-needed basis.

“We all have the shared goal of keeping public safety paramount,” he said. “I want to reassure this board we’re not going to give any less attention to the dam. We’re actually improving our ability to keep a close eye on the dam.”