Anglers and waterskiers started heading back to Lost Creek Reservoir Tuesday after public-health officials lifted an advisory against water contact triggered by a bloom of potentially toxic blue-green algae.

Anglers and waterskiers started heading back to Lost Creek Reservoir Tuesday after public-health officials lifted an advisory against water contact triggered by a bloom of potentially toxic blue-green algae.

Tests on water sampled last week showed that levels of algae and any toxins associated with it were well below safety thresholds, allowing the state Department of Human Services to lift the advisory in place since June 4.

U.S. Army Corps of Engineers officials began taking down signs warning people to avoid contact with the water and to keep their pets away.

"It's definitely a relief once those signs go down," said Doni Swearingen, manager of the Lost Creek Lake Marina, where business has been at a crawl throughout most of the advisory.

"It's gone in time for the Fourth of July, so life is good," Swearingen said.

Lost Creek Lake, Jackson County's largest reservoir, sits atop the Rogue River 30 miles north of Medford.

Tuesday's action leaves Willow Lake in eastern Jackson County as the only water body in Oregon with a current blue-green algae advisory.

The Willow Lake advisory went into effect April 21. Tests on June 8 showed algae levels hovering just above 100,000 cells per milliliter of water — the World Health Organization threshold for what is considered safe.

Jackson County Parks Department managers plan to take water samples today at Willow Lake. They hope the tests, similar to those done last week at Lost Creek Lake, will be favorable.

If so, the advisory against water-contact at Willow Lake could be lifted as early as June 30.

"We'll be sampling (today) with the hopes of getting it lifted before the Fourth of July weekend," said Steve Lambert, county parks manager.

Summer algae blooms have been the bane of Lost Creek and other reservoirs throughout Oregon in recent years, with 29 public-health advisories issued across Oregon last year.

Blue-green algae is a bacteria normally associated with hot weather, when nutrients such as nitrogen or phosphorus are high in the water. The algae can release toxins when it dies, and advisories typically last for two weeks after the algae disappears to allow time for toxins to dissipate.

However, state DHS and WHO protocols allow for the lifting of an advisory one week after tests show less than 100,000 algae cells per milliliter of water and less than 1 part per billion of algae-related toxins in the water.

Tests at four Lost Creek sites returned Monday showed no trace of toxins and algae levels ranging from 700 cells per milliliter to 4,124 cells per milliliter, said Chad Stuart, the Corps' natural-resource manager in the Rogue River basin.

The toxicity tests cost about $450 apiece, but they are invaluable for speeding up the clock on the advisory, said Jim Buck, the Corps' Rogue basin operations manager.

"We want first and foremost to have public safety, but we wanted to minimize the impact to the upper Rogue by having the advisory lifted as soon as we could," Buck said.

Lambert said county parks will not pay for the toxicity test for Willow Lake water until the algae tests — which cost about $150 — show acceptable levels.

Until then, people and pets should avoid skin contact with the water and avoid swallowing or inhaling water droplets. Health officials also warn people not to eat fish, crayfish or freshwater shellfish taken from Willow Lake while the advisory is in effect.

However, boating and catch-and-release fishing are not part of the voluntary advisory.

Public health officials advise campers and other lake visitors that toxins cannot be removed by boiling, filtering or treating the water with camping-style filters.

Reach reporter Mark Freeman at 541-776-4470, or e-mail at mfreeman@mailtribune.com.