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Columbia’s high flows helping dilute sewage spill

Mon., June 25, 2012, 3:24 p.m.

High flows in the Columbia River helped dilute sewage spilled into Lake Roosevelt over the weekend from a British Columbia treatment plant, local health officials said.

Heavy rains overwhelmed a municipal treatment plant in Trail, B.C., causing river water to back up at a pump station. The spill was contained Saturday afternoon after about six to eight hours, said Bryan Teasdale, the plant’s operations manager.

Teasdale said he doesn’t yet know how many gallons of sewage entered the Columbia, but said the release was less than a March leak, when 1.15 million gallons of effluent flowed into the river.

An earlier estimate from the Washington Department of Ecology was 2.6 million gallons of sewage effluent. No solids were released. The treatment system serves the communities of Trail, Rossland and Warfield, B.C.

Some downstream residents in Northport, Wash., reported a sewage smell. The Tri-County Health District encouraged people who came into contact with river water to take precautions, including avoiding ingesting the water and washing their hands.

Cool temperatures limited the number of swimmers in Lake Roosevelt last weekend, but plenty of anglers were on the river for a walleye tournament, said Matt Schanz, the district’s environmental health director.

Flows in the Columbia were running at 281,000 cubic feet per second at the international border. “The dilution factor is enormous, which helps the situation,” Schanz said. Sunlight also helps break down the pathogens from the sewage effluent that could cause sickness, he said.

But he urged people recreating in the area to take precautions for a few more days.

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