U.S. Army Corps of Engineers technicians today plan to investigate whether a blue-green algae bloom at Lost Creek Lake has dissipated less than two weeks after it began, unlike the months-long blooms that have plagued the reservoir during the fall in recent years.
A Corps boat crew plans to scour the nooks and crannies of Jackson County's largest reservoir to see whether the bloom of cyanobacteria is dying off, which could trigger a waiting period before the volunteer advisory against water contact can be lifted.
"I want to check the lake entirely to make sure it's not hiding somewhere," said Justin Stegall, the Corps' natural resources manager at the reservoir. "If it's clear, we'll start the testing."
Before the voluntary advisory against water contact there can be lifted, water tests are needed showing that no toxins are being released by the dying algae.
If the tests are clean, it will represent a remarkable turn of events at the reservoir, where fall algae blooms have triggered some of the longest-lasting advisories Oregon has ever seen.
In each of the past three Septembers, blooms that hit in mid-September lasted at least until late December, with two lingering into the new year, according to Oregon Health Authority statistics.
Last year's bloom triggered an advisory that began Sept. 18 and lasted 128 days before it was lifted Jan. 24.
The lake has also seen midsummer outbreaks, but those tend to die off in less than a month, OHA statistics show.
This latest bloom of anabaena flos-aquae led to a Sept. 13 advisory against water contact there.
But Corps rangers Friday noticed a marked difference in the greenish hue associated with algae outbreaks, particularly in the waters upstream of Peyton Bridge, where Highway 62 spans the 36-year-old reservoir.
"If the lake has cleared up, that would be very unusual," said Jim Buck, the Corps' Rogue River Basin project manager.
Last year's fall bloom was also caused by anabaena flos-aquae, one of the three most common forms of cyanobacteria found in Oregon waters. It can produce toxins that are potentially fatal to people and pets that ingest them.
Blooms in 2010 and 2011 were caused by the cyanobacteria aphanizomenon, which was recently taken off the harmful algae list after it was determined it does not produce harmful toxins, said Rebecca Hillwig, who manages OHA's Harmful Algae Bloom Surveillance Program.
Aphanizomenon outbreaks in Oregon tend to last longer than anabaena flos-aquae outbreaks, Hillwig said.
During advisories, people and pets are warned to avoid all water contact, but compliance is voluntary. Anglers are encouraged to practice catch-and-release fishing during advisories.
Toxins cannot be filtered by standard camp filters or by boiling the water. In-home filtering systems cannot cleanse the water, though public treatment plants can reduce algae toxins through filtration and disinfection.
People who eat fish from algae-tainted waters should remove all fat, skin and organs before cooking because toxins can collect there. People should not eat crayfish or freshwater shellfish taken from infested lakes during an advisory.
No confirmed human illnesses have been tied directly to an algae outbreak in Oregon. However, at least four dogs have died in recent years from toxins in water near the Umpqua River near Elkton.
Hillwig said no confirmed sicknesses have been reported so far this year.
In addition to Lost Creek Lake, three other Oregon water bodies have blue-green algae health advisories in effect. They are Devil's Lake near Lincoln City, and Fern Ridge Reservoir and Walterville Pond in Lane County.
Reach reporter Mark Freeman at 541-776-4470 or firstname.lastname@example.org.