Algae reach harmful level at reservoir

Published 5:00 am Tuesday, August 24, 2004

High levels of blue-green algae that can release toxins harmful to people and animals prompted health department and Forest Service officials to post advisories Friday at Crane Prairie Reservoir’s Rock Creek Campground that recommend avoiding water contact and boating.

Advisories on the rest of the reservoir simply recommend avoiding water contact. Rock Creek Campground and boat launch advisories also warn against boating because officials are concerned people and their pets could come in contact with the water while launching and navigating watercraft.

”For some reason, the algae seem to have collected in that part of the reservoir,” said Tom Walker, a Deschutes National Forest fisheries biologist who has been collecting water samples throughout the forest. ”It probably has a lot to do with prevailing winds.”

No other health advisories are posted on Deschutes National Forest lakes.

Officials have not closed any lakes this summer. Instead, they have posted advisories to inform the public of possible health risks associated with high blue-green algae levels.

Algae densities should naturally dissipate as summer ends. Oregon Department of Human Services, Deschutes County Health Department and Forest Service officials plan to take down Crane Prairie Reservoir advisories after test results demonstrate low cell counts for two consecutive weeks. This is because toxicologists’ reports of toxin level drops often lag behind declines in algal populations.

Toxins are often highest near the end of a blue-green algal bloom, when they are released from decomposing cells, according to scientists.