Public-health officials hope a water sample taken Thursday from Willow Lake will start the countdown on a 4-week-old advisory against water contact there because of a potentially toxic blue-green algae bloom.

Public-health officials hope a water sample taken Thursday from Willow Lake will start the countdown on a 4-week-old advisory against water contact there because of a potentially toxic blue-green algae bloom.

But even if Thursday's samples show algae levels are dying, the advisory that has kept campers and anglers away from this High Cascades reservoir likely will not be lifted until after Memorial Day.

Health officials typically wait two weeks after receiving an all-clear test before lifting the voluntary advisory. In this case, that would be June 3.

"The advisory's still in effect," said Jennifer Ketterman, the program coordinator for the state Department of Human Services' Harmful Algae Bloom Program. "Hopefully, we'll have some good news here soon."

Despite cold-weather conditions not normally associated with algae blooms, Willow Lake in mid-April sported levels of blue-green algae that were 52 times higher than World Health Organization thresholds considered safe for contact by people and pets.

Under the advisory issued April 21, people and animals should avoid swallowing or inhaling water droplets and skin contact with the water. Health officials also warn people not to eat crayfish or freshwater shellfish taken from Willow Lake while this advisory is in effect.

However, boating and catch-and-release fishing were not part of the advisory, and people can safely eat fish caught during the advisory if they first remove all fat, skin and organs.

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.

Blue-green algae has been the bane of inland Oregon waterways this decade, when its discoveries prompted 29 public-health advisories last year alone.

Willow Lake remained Thursday as the only Oregon water body currently under a harmful algae advisory, Ketterman said.

— Mark Freeman