BLEWETT PASS — A truck hauling bio-solids from a sewage treatment plant overturned on an icy patch of Highway 97 at Blewett Pass and spilled 15 tons of the clumpy waste into Swauk Creek, officials said. The driver was shaken but escaped injury in the accident early Monday on the way from Woodinville to a farm in Douglas County. Officials from King and Kittitas counties and the state Ecology Department went to work immediately on the cleanup. By early Tuesday, all the bio-solids that could possibly be cleaned up had been removed by a vacuum truck, said Jessie Israel, Resource Recovery Section manager with King County’s Wastewater Treatment Division.

County and state workers will monitor the creek for about a week. People and pets are advised to stay out of the water, because the bio-solids contain fecal coliform bacteria, said Kittitas County Environmental Health Supervisor Holly Myers.

The contamination should be safely diluted by the time anything reaches the Yakima River, Israel said.

Bio-solids are a sewage treatment plant byproduct used as a soil amendment or fertilizer. The materials are 95 percent pathogen free and remaining pathogens die off within days of exposure to soil and air, Israel said. The state Ecology Department regulates the application to limit public contact.

King County moves about 10 big trucks of bio-solids a day from three treatment plants at Woodinville, West Seattle and near Renton, Israel said.

The bio-solids have gone through treatment plants and look like clumpy soil, Israel said.

“The material going out is nothing like the material going in,” she said.