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Mud Lake dam right on target

by Linda Hiller

Construction on the new, improved, more earthquake-safe dam at Mud Lake Reservoir is right on schedule, according to Jim Usher, Bently Agrowdynamics general manager.

“We started construction in January and should be done before July 1,” he said. “Everything is going along as planned.”

The original clay-filled dam, built in 1902 by Carson Valley pioneer William F. Dressler, was damaged in a 1994 6.0 earthquake centered in the Double Spring Flat area south of Gardnerville.

A subsequent inspection of the then-92-year-old structure resulted in it being listed as a “high risk” dam, although the damage wasn’t bad enough to mandate rebuilding. But Bently, who purchased the dam and reservoir in 1996, went ahead with the estimated $7 million construction of the new dam, to be safe.

“Eventually a quake will hit and we wish to be prepared,” he said in a December press release.

Bently has retrofitted his Valley business buildings to withstand an 8.0 earthquake, and is one of the most visible earthquake-conscious business leaders in the area.

– Shape is done. Usher said the new dam is being built downstream from the 1902 structure. This week, he said, the rock and gravel embankment was completed to its “crest height.”

The rock fill is intended to remain intact in the event of an earthquake of any type.

“Even if it’s wet, the gravel will stay intact in an earthquake, whereas if things are super-saturated, you can have that liquid earth situation, but not with this design,” Usher said.

The next steps in the dam construction are the installation of a waterproof plastic liner on the face of the dam and a 3-inch layer of concrete over that.

“The concrete protects the waterproof liner from the elements, including ice, wind and sunlight,” Usher said. “Plus, it provides a rougher surface for wildlife. They’ve had problems with just the plastic liner being on the outside, because animals can’t get a grip on it and slip off.”

Mud Lake is a well-known wildlife habitat, with thousands of birds including ducks, pelicans, terns, gulls, wading birds, shorebirds, passerines, raptors and more, frequenting the area each year.

– Important irrigation storage. Most of the water stored in the reservoir is used in the irrigation of Bently Agrowdynamic’s South Ranch, located near the Ranchos.

The 300-acre reservoir, located south of the Gardnerville Ranchos, has a storage capacity of approximately 5,500 acre feet.

Usher, 28, who has been Bently Agrowdynamics’ general manager for one month, said construction already completed on the dam, built downstream from the old structure, also includes a 7,600-foot pipeline that will deliver irrigation water from the reservoir to the South Ranch by pressure.

After the new dam is completed this summer, the old structure will be gradually breached, Usher said. Kiewit Pacific Stone and Webster, a joint venture, is the general contractor and designer for the dam’s construction, he said.