The popular Little Hyatt Lake has been closed to recreationists because the 84-year-old dam that created the lake is leaking more water and appears more unstable in just the past few days.
The U.S. Bureau of Land Management on Thursday also closed the county road over the downstream side of the 84-year-old structure and rerouted a section of the Pacific Crest Trail immediately downstream from the dam on Keene Creek, said Jim Whittington, spokesman for the BLM's Medford District.
Although no one lives in the flood plain below the 18-foot-high dam, local residents have been notified about the changes, he said
"At this point, no one can predict if there is an imminent collapse or just more leakage, but given the changes observed in the dam over the last few days, we absolutely have to err on the side of safety," said John Gerritsma, the BLM's Ashland Area Resource Manager, in a prepared statement.
The closure comes at a time when a local group called Save Little Hyatt Lake gathered 919 signatures over Labor Day weekend from those opposing the dam's removal. 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.
The agency was already considering whether to buttress the crumbling concrete with boulders or breach the dam when a BLM employee checking on the dam Wednesday noticed that more water appeared to be leaking through one area compared to a week ago.
Photographs taken Aug. 30 of the leaks compared to those taken Wednesday confirmed that suspicion, Whittington said.Moreover, some cracks that were leaking on the west side have stopped leaking, prompting agency engineers to be concerned that materials in the dam could be shifting, he added.
The increased flow is in a section of the dam identified as the most likely area for a collapse in a 1999 engineering study by an independent firm. BLM dam specialist Doug Laird described the increased leaking as significant.
"Our engineers are worried not only about the increased leakage, but also about the cracks that have stopped leaking," Whittington said. "We are going to drain it completely as fast as we can to relieve the pressure on the dam."In addition to installing a siphoning system, the agency will also employ pumps to drain it, he said.
One of the pumps was expected to be working by late Thursday while two others were expected to be in place by this morning.Meanwhile, the BLM have asked the engineering firm OTAK, an international company with offices in Bend and Lake Oswego which examined the structure in 1999, to re-examine it.
In the earlier assessment, the firm had determined the dam poses a safety hazard because of crumbling concrete.The goal is to have the OTAK engineers on-site by this coming weekend, Whittington said.
In addition to having them inspect the dam, the agency may also request they do an analysis, he added.The BLM considered breaching the dam in 1998, but at the urging of local residents conducted an environmental study and decided in 2003 to replace it. But a safety inspection in July 2006 determined the dam had deteriorated to the point of becoming a safety concern.
Hopes of replacing the dam were scuttled after the agency couldn't come up with the money for the job, estimated at more than $1 million.
An environmental analysis and decision for a long-term solution to the dam's structural integrity is expected next week pending a dam inspection and an analysis of the cost of repair by OTAK, Whittington said.
The dam is about a mile downstream from the Hyatt Lake Dam and some three miles upstream from the Keene Creek Dam.
Little Hyatt Lake closed