UPDATE July 12:

Investigators have determined Sunday's sewage leak came from a privately owned pipe, not a city sewer line, officials said Wednesday.

A sewer line was mistakenly connected to a privately owned pipe for rainwater, according to the Portland Bureau of Environmental Services.

Crews continue to clean up the sewage spillage and investigators are still trying to pinpoint the exact source of the sewage pipe's connection to the rainwater pipe.

The public should continue to avoid Woods Creek, officials said.

***

Officials are warning the public to stay away from two Southwest Portland creeks after about 27,000 gallons of sewage spilled into the waters.

The sewage spilled into Woods Creek in the 6100 block of Southwest Canby Street on Sunday, the Portland Bureau of Environmental Services said in a news release. Woods Creek feeds into Fanno Creek.

Maintenance crews estimate 27,000 gallons spilled into the creek before they diverted the flow into a nearby sewage line.

The bureau is investigating the cause of the spill and working on repairs, said spokeswoman Diane Dulken. Most sewage spills are caused when grease, tree roots or other debris block pipes, she said.

The bureau asks that the public avoid Woods Creek and Fanno Creek in the area of the spill for at least 48 hours due to the possibility of increased bacteria in the water.

The bureau also advises people not to flush anything other than waste or toilet paper and not to put anything down storm drains.

— The Oregonian/OregonLive