October 12, 2012  11:50 AM

Only in Oregon: Beaver dams blasted to save dying ducks

It's the kind of thing that could only happen in an Oregon autumn – the work of the beavers was blasted to help out the ducks.

In this case, the blast was literal – 144 pounds of explosives, used to help drain out Smith Lake in North Portland in ongoing efforts to curb an avian botulism outbreak at the wetland.

The outbreak, in its second month, has killed hundreds of birds and had subsided considerably after lasers and air cannons were used to scare birds away from the wetlands.

See also: Cannons, lasers used to scare birds from disease-ridden natural area (Sept. 27, 2012)

But officials from Metro's Sustainability Center, which manages the Smith and Bybee Lakes Wetlands Natural Area, found that a few dozen birds per day were still dying at the natural area.

"Any waterfowl that spend significant time at Smith or Bybee lakes are getting sick," said Jonathan Soll, the Science and Stewardship Division manager for Metro's Sustainability Center.

An influx of cold rain will eventually help to wash away the toxins that are making the birds sick. But Soll said it could be some time before enough rain falls at the lakes to flush out the outbreak.

So officials decided to try to drain out Smith Lake. Bybee Lake was already drained, but beaver dams at Smith kept it filled with water.

Deconstructing a beaver dam, though, is not as simple as thinning it with a chainsaw, Soll said.

"You can only get to a certain point that way, and then the accumulated sediment in the channel from the beaver dams over time was just something that could not be dealt with," he said.

The obvious answer at that point was to use heavy equipment to break up the dams, but the muddy earth surrounding the dams made it impossible to load a tractor or spider hoe to the beaver dam sites.

That's when the explosives came out, with a professional demolition company breaking up the dam and clearing sediment that had accumulated in the drainage channel.

"The blasting went well, and safely, and was quieter than the hazing," Soll said.

He couldn't say if any beavers were harmed in the blasting, but he said it was extremely unlikely. Crews will be watching to dismantle any dam rebuilding attempts by the beavers.

Wildlife officials emphasize that the risk to humans from the outbreak is low.

Metro News editor Nick Christensen can be reached at nick.christensen@oregonmetro.gov or 503-813-7583. Follow Metro on Twitter @oregonmetro.

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