Leavitt Reservoir questions addressed

Shell Bar was filled to the brim Thursday, Sept. 17 as community members gathered to ask their burning questions about the Leavitt Reservoir expansion project. When will the reservoir finally be full, so the Shell Yacht Club can set sail? Was there a leak? Did you find a dinosaur?

Don Scott, project manager for Montana Civil Contractors, has been on-site at Leavitt Reservoir in Shell Valley before the crew even broke ground in 2023. At the request of Wild West Dino Den President Erik Kvale, he volunteered to speak to the public last Thursday. 

Kvale said he had been on a field trip where some of the company trailers were. “I just happened to mention some of the rumors, and I can see [Scott] going, ‘What?’ So anyway, he’s here to address every rumor you’ve heard,” Kvale informed the crowd. 

SCHEDULE

Scott began his talk with a rundown of the Leavitt timeline: In early 2023, Montana Civil Contractors and Big Sky Civil began surveying and stripping borrow pits to create aggregate with the help of crushing company Fisher Industries. Dam construction began in spring 2024. 

When the project did not meet its substantial completion deadline of Dec. 31, 2025, earthwork was considered part of the delay. Kevin Mininger of RJH Consulting, the engineering firm for the project, reported at the time that the embankment foundation required 100,000 more cubic yards of excavation than expected. 

Scott further explained Thursday that the silt from the old reservoir ranged from 15-25 feet, an “endless goo” which needed to be excavated to get to foundation. 

“Everybody’s asking me why we’re digging such a big hole, ‘I thought we’re building a dam, not digging a hole.’ But we were digging a hole to get down to actual foundation bedrock materials and then fill that hole back in and start building a dam,” Scott said. 

Processing embankment fill was also a difficulty, with hard nodules in the onsite mudstone damaging equipment.

“The amount of aggregates that had to be produced for the project was quite large, and the cost that would accrue if we had to import all those from various locations would have been way over budget for what they had anticipated for the project,” Scott explained. The project’s main import was sand, from Greybull, which Scott estimated at 100,000 tons. 

Another reason given for the delay, which resulted in a one-year extension on the project, was that the construction contract for the irrigation water distribution system was nine months later than expected due to insufficient funding. Scott reported the project has stuck to its latest budget, $88 million. The cost will be 98% covered by state funding, the remaining 2% by irrigators. 

This summer Leavitt Reservoir was filled to about 640 acre-feet to satisfy existing water rights, slightly more than that to prevent water erosion. When full, the new reservoir will be capable of holding about 6,600 acre-feet of water and stand about 40 feet at its deepest point. Recreation pool is around 1,500 acre-feet. Scott assured the public that the boat ramp was built to accommodate the lower recreational pool, extending about 250-300’. 

“Hopefully, you guys can back up straight,” Scott joked. 

A 90’ tower in the reservoir is equipped with a staff gauge that can determine the exact water level. Mark Michelena is expected to monitor water levels in the future for Shell Valley Watershed Improvement District. 

As for when the reservoir could reach its fill mark, Scott gave a tentative date of late June 2028. Safety measures require the reservoir to be filled at a controlled rate, and Mother Nature must first supply the runoff to Beaver Creek before the water can be stored. Scott shared that data from previous years suggests the reservoir could be filled 8-of-10 years. 

After late season irrigation wraps up at the end of September, the reservoir can start refilling. 

RUMOR HAS IT

Shell Valley is known for its dinosaurs. While Scott said none were found in the Leavitt project excavation, fragments of bone were uncovered and studied by a paleontologist reporting to Bureau of Land Management. BLM did not respond to requests for comment before deadline. 

Another interesting discovery was the “unnamed tributary,” a sandstone formation producing a small amount of spring water that will minorly supplement Beaver Creek flows. 

The reservoir is almost empty as irrigation season nears its end. Regarding an alleged leak, Scott reported the dam itself is not leaking. However, a toe drain designed to drain groundwater from the reservoir when filled is, as designed. 

“They always say a leaky dam is a good dam,” Scott said. 

WHAT’S LEFT

The Leavitt project should be finalized in late October, Scott said. 

“The joke was that we can release water until September 30, and we start filling October 1. So that leaves me September 31 to do my inspection,” Scott told the crowd. 

Several Shell Valley residents thanked Scott for the effective traffic and dust control measures taken over the course of the project. Concern was presented about the state of the county road, which heavy truck traffic has done a number on. Scott reported that Montana Civil Contractors have reclaimed asphalt and millings and repacked the road surface where Big Horn County requested. Mountain Builders reportedly placed asphalt at key locations. Scott said the county had approved of the restoration to his knowledge, though no final approval had been received. 

Sediment deposit was also a concern. Wetlands north of the dam site are expected to mitigate some sediment buildup issues. Scott said that some locations dredge the material out once enough has built up. At Leavitt, builders are considering keeping a cofferdam that has supplied construction water in place to keep sediment away from the headgate. 

Gravel will be put down through September, borrow pits reclaimed this fall; fencing and recreational features -- picnic tables, a BBQ grill and fire pit -- are the final details. 

OTHER SHELL NEWS

Since a big chunk of Shell was already in the bar, Kvale announced Wild West Dino Den hoped to begin tours of its exhibit at the Historic Red Shell School in about two weeks, scheduled for Saturday afternoons. 

Jeff Schmidt, Big Horn County Search and Rescue south captain, was also called up to announce the organization’s Land Rover Defender award, including a new vehicle and $30,000 grant.