Whetstone Pond algae not the toxic kind

What's the latest on the toxic algae explosion at Whetstone Pond on the Denman Wildlife Area? Is it still there? If not, what is the state going to do about it?

— T.A., email submission


Well, T.A., it turns out that vast mat of toxic algae wasn't what it appeared to be.

Tests at a lab in Seaside determined that there was a small amount of blue-green algae in the mat, but it was a nontoxic strain of cyanobacteria, according to the report. None of the dangerous cyanobacteria that produces toxins were found in the sample, the report states.

The vast majority of the stuff turned out to be a diverse mix of plant fragments, small plankton and phytoplankton, with this algae community dominated by stuff called diatoms, the report states.

"While the sample was thick in consistency and most likely unpleasant to look at, the phytoplankton present were all those normally found in a pond during the summer," the report's summary states.

In other words, the scientific word for what's out there is ... gross.

The pudding-like algae mats started to show up at Denman more than three years ago. The algae has taken over about 30 percent of the 5-acre pond, and the crusty mat has choked off the boat ramp and irrigation pipe there.

It has grown progressively worse, leading to earlier tests that identified aphanocapsa, which can cause toxins, leading the Oregon Department of Fish and Wildlife to ask for the Seaside lab's assessment.

For now, the grossness will remain the status quo, but Denman Manager Clayton Barber says he's discussing some potential solutions.

Tests have shown that Whetstone Creek is high in phosphates, whichis a key ingredient to grow this algae. So one possibility is to introduce some special vegetative mats that process the phosphates and help keep the algae from growing, Barber says.

The pond ultimately will have to be drawn down and deepened, which is a pretty spendy endeavor, Barber says.

So who or what might pay for the big fix at Whetstone? One potential source is the state Restoration and Enhancement Program, which takes money from surcharges to fishing licenses to restore and enhance fish habitat in Oregon.

The Restoration and Enhancement Board, which oversees the program, met Friday at Denman. Barber says he filled the board in on the problem, in case he ends up applying for a grant to address the algae.

— 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 youasked@mailtribune.com. We’re sorry, but the volume of questions received prevents us from answering all of them.

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