Potential for the failure of Little Hyatt Lake dam has been lowered dramatically after a week of draining the lake.
"We've reduced the hazard significantly," said John Gerritsma, the U.S. Bureau of Land Management's field manager for the Ashland Resource Area.
"The pressure on the dam and any potential for collapse is way down," he added. "There is a noticeable difference in leaks in the dam without the pressure from the higher water in the lake."
Concerned about the structural integrity of the 18-foot high dam built in 1923, the BLM began drawing down the 11-acre reservoir on Sept. 7 to relieve pressure on what engineers have said is crumbling concrete in the structure.
"We've got it down to around the 8-foot level at the dam," Gerritsma added. "It's probably about 50 percent of the original depth of the lake from when we started."
He estimates the water level is now roughly 20-acre feet, meaning there is enough volume to cover 20 acres with a foot of water.
The popular reservoir on Keene Creek was closed to recreationists on Sept. 6 after officials noticed increased water leaking from the dam. The county road immediately downstream from the dam also has been closed and the section of the Pacific Crest Trail near the dam has been rerouted. No one lives in the flood plain downstream.
The area remains closed because of the equipment in the area, Gerritsma said, noting that the draining work continues around the clock with pumps and siphons.
Fish traps installed in the lake to capture trout have caught some 2,800 dace &
small trout &
and about 15 large rainbow trout, including one lunker about 20 inches long, according to Kevin Kocarek, a BLM fish biologist with the Ashland Resource Area.
"We got way more than we expected," Kocarek said of the trapping that began Wednesday night.
The trout were transported to Hyatt Lake about a mile upstream and released, he said. They also caught about 300 invasive bullhead catfish which were disposed of, he added.
"We want to get as many fish out as possible," he said. "We're expecting to get about the same amount through the weekend."
Fish trapping is expected to continue for up to about two weeks. The BLM is working with the Oregon Department of Fish and Wildlife and the federal Bureau of Reclamation, both of which have provided equipment for the trapping project.
The agency is considering whether to buttress the crumbling concrete with boulders or remove the dam. The lifespan of the concrete used to build the 84-year-old dam is 75 years.
A local group called Save Little Hyatt Lake has gathered more than 900 signatures from those wanting to keep the dam. Copies of the petitions were given to the offices of U.S. Sens. Ron Wyden and Gordon Smith and U.S. Rep. Greg Walden, all of Oregon.
Group members have said they aren't opposed to draining the reservoir to allow the dam to be examined but hope the agency will buttress it instead of breaching it.
The agency has asked engineers from OTAK, an independent engineering firm whose late 1990s study estimated the cost of repairs to be about $430,000, to re-examine the dam. Those engineers have not yet arrived.
At this point, the goal is to draw the lake depth at the dam to around six or seven feet, Gerritsma said. The agency plans to rely on the siphoning system since it's cheaper than using pumps, he said.
But the agency has to keep enough water running in the stream for power generation and for irrigation downstream. The Keene Creek Dam is about three miles downstream.
Meanwhile, nothing unusual has been found in the reservoir, which officials believe hasn't been drained since the dam was built.
"We haven't found anything but a lot of muck," Gerritsma said.
Pressure eased on Little Hyatt Lake