A potentially toxic blue-green algae bloom at Lost Creek Lake has prompted Oregon State Parks officials to cancel a Free Fishing Weekend event planned there Saturday.
The Oregon Health Authority on Tuesday afternoon issued the volunteer advisory — the first this year in Oregon — after the discovery of a large bloom of the cyanobacteria at Jackson County's largest water body.
Water tests showed more than 3.2 million cells per milliliter of Anabaena flos-aquae, a cyanobacteria that has bloomed regularly in late spring at the Rogue River reservoir 30 miles north of Medford, according to the U.S. Army Corps of Engineers, which operates the lake.
Anabaena flos-aquae can produce potentially dangerous toxins, particularly when the bloom dies off. But not all blooms end up toxic. The threshold for a public-health advisory in Oregon is 100,000 cells per milliliter.
State parks officials today opted to cancel the event.
However, the Oregon Department of Fish and Wildlife plans to release 5,250 rainbow trout there this week as planned.
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.
Boating and fishing are considered safe so long as boat speeds do not create excessive water spray, according to health officials.
Exposure to toxins can produce symptoms of numbness, tingling and dizziness that can lead to difficulty breathing or heart problems, and require immediate medical attention. Symptoms of skin irritation, weakness, diarrhea, nausea, cramps and fainting should also receive medical attention if they persist or worsen.
Children and pets are at increased risk for exposure because of their size and level of activity.
The public will be advised when the concern no longer exists.
Not all blue-green algae strains produce toxins dangerous to people or pets, and not all blooms release toxins.
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.
While the toxins associated with the algae blooms have killed at least four dogs in Oregon in recent years, no human sickness or death has been directly linked to blue-green algae toxins, according to health officials.
— Mark Freeman