Toxic algae is slow to leave Lost Creek Lake

Why is the blue-green algae advisory warning still in place at Lost Creek Lake? Hasn't it been cold enough for the algae to die like it normally does in the fall?

— Dan D., via email

That pesky fall blue-green algae outbreak that seems to plague Lost Creek Lake in the fall finally seems to be breaking up.

U.S. Army Corps of Engineers rangers earlier this week noticed the greenish hue in the lake finally to be waning, says Jim Buck, the Corps' operations manager at the reservoir along the Rogue River in northern Jackson County.

If visual inspections continue to show an apparent die-off of the algae, Corps officials will take water samples later this week to test for the presence of the cyanobacteria commonly called blue-green algae and any toxins associated with them, Buck says.

If the tests don't show levels of cyanobacteria or toxins above unhealthy levels, the results will be forwarded to Oregon Public Health officials, who typically then lift the all-volunteer advisory.

Since the outbreak in mid-September, Corps officials have been regularly watching the bloom and have not seen it disperse enough to proceed with water-quality tests, Buck says.

Mid-September water samples showed Anabaena flos-aquae levels in the reservoir at 405,900 cells per milliliter of water. The threshold for advisories is 100,000 cells per milliliter.

Tests on water released from the reservoir into the Rogue came back at only 247 cells per milliliter, so the advisory was relegated only to the reservoir.

Whether this week's changes trigger a removal of the advisory remains to be seen.

In the past, September blooms have lingered into January, records show.

And Lost Creek's not alone.

Public-health records show that blue-green algae advisories remain in effect at four other Oregon reservoirs: Fern Ridge and Dexter reservoirs in Lane County, Big Creek Reservoir in Lincoln County, and Willow Reservoir in Morrow County.

Until the Lost Creek advisory is lifted, visitors should avoid skin contact with the water and avoid swallowing or inhaling water droplets, according to the advisory. Boating is safe as long as speeds do not create excessive water spray, which could lead to inhalation risk, the advisory says.

The toxins associated with cyanobacteria cannot be boiled away or filtered, so drinking the water should be avoided.

People who want to eat Lost Creek Lake fish should remove all the fat, skin and organs before cooking.

There never has been a confirmed human illness in Oregon caused by the algae or its related toxins.

However, two dogs have died in past years from algae-related toxins along the Umpqua River near Elkton.

Send questions to "Since You Asked," Mail Tribune Newsroom, P.O. Box 1108, Medford, OR 97501; by fax to 541-776-4376; or by email to We're sorry, but the volume of questions received prevents us from answering all of them.

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