More than 8 million gallons of sewage spilled into a mile-long stretch of Ravenna Creek earlier this month. The spill lasted 10 days, beginning May 13. A leak was reported by the City of Seattle last Friday after utility crews noticed an abnormally high volume of storm water in the creek, despite mild rainfall.

It occurred in a drainage canal running from Northeast 45th Street near Montlake Boulevard to the Union Bay Slough, opening into Union Bay near the UW Waterfront Activities Center.

“It’s a very serious spill, and we take full responsibility,” said Annie Kolb-Nelson, the community relations planner for the King County Wastewater Treatment Division.

After the spill was reported, King County Wastewater Treatment stopped the spill and began testing water bacteria levels while removing paper-product debris from the creek. The day the spill was reported, colony-forming units (CFU) levels were unsafe for human contact, so the area was closed and signs warning waders were posted.

The next day, many of the test points had bacterial amounts 50 percent lower. On May 28 results found that just two of the test sites still had unsatisfactory CFU levels.

“The risk for human illness appears to be low,” said James Apa, spokesperson for the Seattle Public Health Department.

Raw sewage contains a variety of biological agents and can cause gastrointestinal infections and respiratory, eye, ear, nose, throat and skin infections, Apa said.

“If you have felt ill or had diarrhea and had been swimming in the water during the time of the spill, I recommend visiting a doctor,” Apa said. “Be sure to tell them you were swimming in the spill.”

Freshman Blake Engelbert went canoeing and bridge jumping with friends near the Waterfront Activities Center Friday, May 16, three days after the spill began.

“It’s absolutely disgusting,” he said. That weekend temperatures were high, and many UW students and Seattle residents were enjoying the lake.

“It couldn’t have happened at a worse time,” Engelbert said.

King County Wastewater Treatment reported that the spill was caused when a regulator gate was being repaired and the pipe was mistakenly diverted to a Seattle stormwater pipe instead of the Laurelhurst Trunk.

“The drawings our employees were following hadn’t been updated since 2004,” Kolb-Nelson said.

The piping had been switched since the maps were drawn, so no charges of negligence have been placed on the specific employees who redirected the piping.

“The spill appears to be accidental,” Kolb-Nelson said.

Kolb-Nelson said the division is working to fix the drawings to avoid any future spills.