A break in a pressure sewer caused a sewage leak Wednesday afternoon at the Fanno Pump Station in southwest Portland.

The pump station is at 6895 SW 86th Avenue. Most of the sewage was contained at the site, but some flowed overland into nearby Fanno Creek.

People should avoid contact with Fanno Creek downstream of that area through this Friday afternoon, officials said. Environmental Services and Clean Water Services staff posted warning signs at public access points downstream of the spill.

The sewage in the pressure line was mixed with sodium hypochlorite, a mild bleach solution used to reduce odors in the line. Witnesses estimate the amount of combined sewage and sodium hypochlorite that reached Fanno Creek was less than 50 gallons.

The pump station has been shut down since March 13, when another section of the same pressure line broke near SW 77th and Garden Home Road. Maintenance crews finished repairing that section this morning. Pump station crews had just re-activated the Fanno Pump Station to test the repair when they discovered the new leak.

The pump station is offline again while maintenance crews find the cause of the new leak and plan repairs.