PORTLAND, Ore. (KOIN) – A malfunction at a Lake Oswego water treatment facility led to 500,000 gallons of non-disinfected wastewater to flow into the Willamette River overnight near Foothills Park, the Portland Bureau of Environmental Services announced Monday.

The city is advising the public to avoid the river in the area for two days out of an abundance of caution due to the possibility of increased bacteria in the water.

According to the city, the wastewater had undergone most stages of treatment at the Tryon Creek Wastewater Treatment Plant except for the final step of adding disinfectant. The pump that delivers the disinfectant failed around midnight and was repaired at 5:30 a.m. officials said.

The City of Portland said it is working with Lake Oswego to replace the aging wastewater plant.