Dam construction set to begin in Logan Canyon

Logan Light and Power has announced plans to begin the reconstruction process and improve the spillway function at Third Dam in Logan Canyon, a diversion spot for the hydroelectric powerhouse providing Cache Valley with electricity.

“The concrete there has been in place for almost 100 years,” Light and Power director Mark Montgomery said. “It is time for some work to be done.”

Work is slated to begin Tuesday and continue for the next two years, but will pause in the summer.

“They will be repairing the concrete and installing an Obermeyer weir under the spillway, basically an inflatable rubber bladder that raises and lowers the spillway gate,” Montgomery said.

Prior to the weir’s installation, Montgomery explained, workers had to raise and lower the spillway gate by hand, a dangerous job during high-water season.

The construction will intermittently affect traffic on the canyon road near Third Dam.

“Lane restrictions will be fairly infrequent, but will be worse next season,” Montgomery said. “We are starting work on the south side, but when they tear down the gatehouse right by the road, there will be lane restrictions or closures.”

Montgomery said Light and Power has been working closely with the Forest Service to manage recreation in the area.

“It should not have much impact on our users,” said Jennefer Parker, the Logan district ranger for the Uinta-Wasatch-Cache National Forest. “They will have equipment in the Logan River Trail, one of the most popular trails, but we have re-routes where users will be able to take a detour.”

Fishermen, however, may be disappointed in the amount of trout near Spring Hollow, just upstream of Third Dam.

“They will be letting out water from the reservoir, so I am assuming the fishing will not be great,” Parker said.

Fish may not be the only wildlife affected, Montogmery said. Construction is restricted in summer partly due to the possible riparian nesting zone of the yellow-billed cuckoo, a rare, threatened bird that favors mid-altitude cottonwood trees near rivers.

“We could probably finish in just a year if able to work in the summer,” Montgomery said.

Parker noted, however, that the bird is not the only reason construction is limited in the summer.

“It is best to do those projects at low water,” she said. “There are restrictions on doing in-stream work during the main season.”

Montgomery said Logan Light and Power’s next projects will focus on sediment dredging in the reservoirs behind Logan Canyon dams.