TRAIL — Lost Creek Lake edged closer Thursday to seeing its public-health advisory against water contact lifted this weekend after tests showed "non-detectable" levels of toxins associated with its recent blue-green algae bloom.

TRAIL — Lost Creek Lake edged closer Thursday to seeing its public-health advisory against water contact lifted this weekend after tests showed "non-detectable" levels of toxins associated with its recent blue-green algae bloom.

But whether the U.S. Army Corps of Engineers's reservoir along the upper Rogue River gets the all-clear for swimmers and water skiers before the Fourth of July hinges on a yet-uncompleted test for concentrations of anabaena flos-aquae, said Jim Buck, the Corps' Rogue River Basin project manager.

If the algae cell count drops below what the World Health Organization deems unhealthy, it would pave the way for the voluntary advisory against water contact by people and pets to disappear possibly within a day, officials said.

"The toxins test is very good news, but we have to get the cell count as well because it's all part of the picture," Buck said.

"It's certainly looking good," he said. "We'll keep our fingers crossed that the counts fall below the levels we're looking for."

Laura Boswell, who tracks algae outbreaks for the state Department of Human Services, said Thursday that her office has yet to see any of the Corps' test data.

Once the data is reviewed and the thresholds pass muster, it takes about a day to reverse an advisory, Boswell said.

"We try to do it as quickly as possible so people can use the lake again," Boswell said. "We just need to see the data."

Health officials on June 15 issued their public-health advisory after water sampled the week before at the state park's swim area showed levels of anabaena flos-aquae as high at 16 times the threshold considered safe for contact.

People and pets were warned not to ingest or inhale any water droplets, which could cause sickness. Also, anglers were encouraged not to eat the fish they catch there until the advisory is lifted.

No adverse health effects have been detected from water contact during three previous algae outbreaks at the lake dating back to 2006.

The algae is its most dangerous when huge mats of it die and release toxins en masse.

In past instances, the Corps used a more standard approach to the algae outbreaks. After the lake visibly cleared of its greenish glow, Corps officials took water samples to find cell counts below the threshold of 100,000 cells per milliliter of water.

Then, they waited the requisite two weeks from the day the samples were taken for the dying toxins to dissipate naturally before they lifted the advisory.

This time, however, the lake appeared to clear quickly and Corps officials took advantage of a second set of protocols that could get the lake advisory-free before next week's Fourth of July holiday weekend.

Under state guidelines, a combination of low algae counts and low toxin counts from the same samples drop the two-week wait down to one week.

A laboratory at the University of California at Davis found no detectable levels of two toxins related to this strain of algae — microcystin and anatoxin-a — in water sampled June 19, Buck said. The tests cost about $400.

The good toxin tests would be moot should high levels of algae remain, triggering the opportunity for another die-off and release of toxin. If the algae test comes in low, the lake would immediately qualify for lifting of the advisory.

Buck said the lake has passed the eyeball test for algae. Now, it needs the lab to match it, he said.

"Visually, I'm thinking they've done their thing," Buck said.

Reach reporter Mark Freeman at 776-4470, or e-mail mfreeman@mailtribune.com.