The Oregon Health Authority has issued a number of health advisories for district reservoirs over the past few years, prompted by high densities of blue-green algae. Cottage Grove, Dexter and Dorena reservoirs in the Willamette Valley, Lost Creek Reservoir in the Rogue Basin, and Willow Creek Reservoir in northcentral Oregon have all been frequent targets.
But lately, leaders and residents of communities that depend on tourism dollars generated by our reservoirs have questioned whether these health advisories are necessary.
According to the OHA, blue-green algae are simple organisms (actually cyanobacteria rather than algae) that occur naturally in warm, calm, nutrient-rich waters, most often near the shore due to wind and waves. Blooms can occur anytime, but are most common between June and September.
If harmful algae are swallowed, they can cause diarrhea, nausea, cramps, fainting, numbness, dizziness, tingling and paralysis. Skin contact can cause rashes or irritation. Children and pets are at greatest risk.
The District’s policy, according to David Tucker, Rogue River Basin Project Operations Section chief, is to visually inspect developed recreation areas. If a bloom is noted, then water samples are tested. If high levels of potentially toxic algae are found, the Oregon Health Authority is informed and will then issue an advisory for the entire reservoir.
“Health advisories don’t mean Corps reservoirs are entirely closed to recreation. We encourage people to enjoy camping, hiking, biking, picnicking, bird watching and other activities, while taking proper precautions to avoid water contact,” said Patti Williams, Portland District’s Natural Resources Management Section chief.
But there’s no doubt that advisories scare away some potential visitors. Only a few types of blue-green algae are known to produce toxins, so communities that depend on tourism dollars generated by area lakes and reservoirs aren’t happy when the OHA declares a health risk based on tests that only confirm the presence of blue-green algae rather than its actual toxicity. They argue that testing for toxins makes more sense than testing for the presence of algae cells.
In fact, several communities in the Willamette Valley, including the city of Lowell near Dexter, Lookout Point and Fall Creek reservoirs, have contracted Oregon State University’s Microbiology Department to perform an independent study of algae blooms in nearby reservoirs to determine if they are even capable of producing toxins.
But there are public safety issues with these new toxin tests that make District managers reluctant to use them.
“Toxin testing only tells us if the specific location being tested contains toxins at that moment,” said Rogue River Basin Project Manager Jim Buck. “For example, we could test a thick bloom one day and find no evidence of toxins, but toxins could be present at other locations on the same reservoir the same day and we would not know. Toxins could also develop the following day at the tested location.”
To ensure public safety, the frequency and scope of testing would have to dramatically increase.
The other main problem with toxin testing, Buck said, is that it does not reinforce our and the OHA’s public safety message of avoiding areas that have a bloom. Visitors may start to assume that blooms that they see aren’t toxic unless told otherwise – a dangerous assumption given the limitations of toxin testing discussed above. Public safety is far better preserved at far less cost by simply keeping lake visitors away from blue-green algae.
“Our current cell count testing procedure is state authorized, cost effective, familiar to the public, and reinforces key safety messages and principles,” said Buck.
And as for those communities that rely on tourism at our reservoirs?
“We are aware of the economic impact to the recreation-based communities,” Buck said. “We have expedited cell count water tests if a negative result would result in the advisory being lifted, especially prior to key holidays, like Independence Day. But when we weigh economic impact against public safety, we will always keep public safety as our top priority.”
For more information about blue-green algae blooms in Oregon, go to this infographic from the Oregon Health Authority.