HELENA — A large pile of boulders has been growing along West Shore Dr. near Canyon Ferry Reservoir since early June. Viewer Kally asked why these rocks are getting piled up, and MTN found out.
The rocks are from the Indian Creek mine near Townsend—they’re removed to access limestone in the mine, and soon, they’ll be used to stabilize parts of the Canyon Ferry shoreline.
“These are going to be used to armor the banks against wave action that’s been causing erosion problems.” Bureau of Reclamation civil engineer Jacob Noland said.
Erosion in areas like the Lorelei day use area and at the Yacht Basin store.
“The actual store is being threatened by the erosion,” Noland said. “It’s literally feet from the edge of the erosion.”
Some places along the reservoir’s shoreline have been eroding since Canyon Ferry Dam was completed in 1954. Today, that’s causing some major issues at some recreation sites.
“So much erosion has happened that actual fire rings, picnic tables would start falling into the lake,” Noland said.
The Bureau of Reclamation has bank stabilization projects planned for recreation sites in 2026 and 2027. Crews will reshape slopes using smaller rocks, and then layer the larger rocks—or rip rap—getting piled along West Shore Dr. on top.
“It basically makes the shoreline hard,” Noland said. “Rocks are hard, they don’t erode.”
Work will take place in March through May of 2026 and 2027, because Noland said that is when the reservoir’s water level is typically lowest.
In all, the project will use about 18,000 tons of rock, to put that in perspective, that is more than 39 million pounds of rock. Noland said the project will cost more than $1 million, but once it is done, work likely will not have to be done again in those areas for a while.
“These areas we protect with this project should last a really long time, maybe 50 to 100 years,” Noland said.
Until bank stabilization work happens, people should be careful in areas experiencing erosion.
“There is a chance the banks can fail and injure or kill people,” Noland said.
