BOISE, Idaho -- City streets got an unscheduled cleaning as a sudsy citrus-scented foam erupted from manhole covers like geysers.

The bubbles spewed from a three-block stretch on the city's east side Thursday after American Linen accidentally released detergent into the municipal sewer lines. The combination of gravity and churning water whipped the soap into a sudsy foam.

"We have never had a situation like this before," said Vince Trimboli, the public works spokesman.

Officials say the company had a malfunction, caused by human error, in its automated detergent loading device, releasing 167 gallons of a harmless but concentrated detergent.

Crews worked during the day to disperse the suds before they reached the treatment facility, then used soft-spray hoses and yard blowers to reduce foam levels closer to the plant.

"It had no effect on the treatment plant at all, and the closer the foam got to the plant, they were able to hose most of it off. None of it has gotten to the (Boise) River," Trimboli said Friday.

Meanwhile, there was a similar problem in Wasilla, Alaska. Clusters of foamy bubbles spewed from the city's sewer lagoon, witnesses said.

"It looked like the texture of something you'd see come out of your washing machine if you overloaded it," said Sue Foster, a student teacher.

Bill Harvey, deputy public works director, said that ice thawing on the city sewer treatment lagoons leaves an accumulation of residue and foam on the surface. He also suspected the treatment plant may have gotten a "good jolt" of soap residue.

Aerators that inject air into the lagoons to churn the water for treatment further stirred up the foam, he said. Then, swirling air currents at the treatment plant created a chimney effect that sucked the foam hundreds of feet into the sky and carried them over the city.

Grandview Inn general manager Sandra Joyner said a maintenance employee scooped up some of the bubbles. They had no smell and were a little bit iridescent.

"It was ridiculous. People were pulling off to the side of the road and running out, trying to catch them," Joyner said.