GREENSPRINGS — Workers began installing equipment Tuesday to drain the reservoir behind the historic Little Hyatt Dam, where crumbling concrete has raised safety concerns.

GREENSPRINGS — Workers began installing equipment Tuesday to drain the reservoir behind the historic Little Hyatt Dam, where crumbling concrete has raised safety concerns.

Once the gear is in place, most likely by Friday, the U.S. Bureau of Land Management will launch a siphoning project to reduce the pressure on the 84-year-old structure. Officials say it could take up to two weeks to drain the water, possibly marking the first time the lake has been drained since the irrigation dam was built in 1923.

John Gerritsma, the BLM's field manager for the Ashland Resource Area, cautioned that no decision has been made to remove the dam that creates an 11-acre reservoir.

"No matter what course of action we take, whether to buttress the dam or remove it, we have to drain the lake," he said. "Some people have mistakenly been thinking we were draining the lake so we could remove the dam. We haven't made that decision. Any decision on that won't be made until after the lake is drained," he added.

If the dam stays, one repair solution being considered would buttress the old concrete structure with boulders.

Gerritsma said a decision is expected by mid-September to enable workers to complete their work before the seasonal rains start early in November.

What lies at the bottom of the reservoir is anyone's guess.

"My guess is mud, maybe an old refrigerator," Gerritsma said, adding, "Nobody is aware of any other time that it has been drained since it was built."

After the water is gone, the condition of the dam should be evident, he said.

"This will allow the public to get a good look at it," he said. "Some folks don't believe the dam is crumbling."

Gerritsma and other BLM officials will discuss the future of the dam with local residents and others interested in its future at a meeting scheduled to begin at 6 p.m. today in the yurt adjacent to the Greensprings Inn.

"Everyone up here wants to keep the dam," said local resident Ron Schaaf. "It's a tough issue for us."

Since the old dam is located between two other impoundments — the Hyatt Lake Dam a mile upstream on Keene Creek and the Keene Creek Dam three miles downstream — it doesn't block fish runs, he noted.

In addition to being a popular recreational attraction, the dam has created an important wetland, according to those who hope to preserve it.

The BLM inherited the structure from the Talent Irrigation District, which was prepared to breach it in 1992. BLM officials agree the dam is an asset to the area, but 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.

The dam was built to divert irrigation water from the Greensprings area of the Klamath Basin over to the Bear Creek basin and into Emigrant Lake. It became obsolete in the 1950s when a new structure was erected downstream to accomplish the same goals.

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 the dam. A safety inspection in July 2006 determined the dam had deteriorated to the point of becoming a safety concern.

An environmental assessment of the dam is expected to be released soon.

"When we drain the lake, it'll give us a great opportunity to do a face-to-face with the dam to see if the earlier evaluations are valid," Gerritsma said. "We'll be able to see if the dam is as bad as we believe it is."

The BLM is working with the Oregon Department of Fish and Wildlife to transfer fish in the reservoir upstream to Hyatt Lake while ensuring non-native fish don't swim downstream into Keene Creek Reservoir.

Reach reporter Paul Fattig at 776-4496 or e-mail him at pfattig@mailtribune.com.