This story was updated Friday at 3:10 p.m. following a city announcement of water test results.
A city of Salem attempt to dispose of excess stock of a wastewater treatment chemical Wednesday morning may have caused bacteria to enter the Willamette River.
But river samples taken downstream from the wastewater treatment facility Thursday showed E. coli levels were safe for swimming.
The city announced Thursday evening that it had discharged 2,500 gallons of sodium bisulfite into the city’s wastewater treatment system, disrupting normal operations at the Willow Lake Wastewater Treatment Facility.
The result is that the chlorine which normally disinfects Salem’s wastewater may have been less effective following the release. That could mean higher bacteria levels in the river.
There’s no health threat to the public, city spokesman Trevor Smith said. The city is working with the state Department of Environmental Quality to monitor the effects, but the agency did not require the city to notify the public of the incident, he said. The city did so voluntarily in an effort to be transparent.
Results from bacteria tests of Willamette River taken at noon Thursday showed the water was well below limits for water recreation.
E. coli levels are measured by the approximate number of bacteria found in a 100 milliliter sample of water. For water to be considered safe for swimming, that number can’t exceed 406 in a test.
The sample upstream from the city’s wastewater plant at Sunset Park recorded 18. Downstream at Spong’s Landing, it was 84.
Sodium bisulfite is a chemical the city has used in the past to neutralize extra chlorine added to the city’s drinking water.
After a 2018 toxic algae bloom in Detroit Lake contaminated Salem’s drinking water, the city beefed up its water treatment protocols. That included adding extra chlorine to the water to remove toxins when needed.
After the chlorine has killed toxic bacteria, the sodium bisulfite is added to water to dechlorinate it and make it safe to drink.
But since the city upgraded its water treatment facilities with ozone treatment in 2022, there’s been little need to have the sodium bisulfite on hand, Smith said.
Public works employees planned on Wednesday to dispose of the excess chemical by dumping it at the city waste processing facility on Southeast Airport Road. It’s the same location portable toilets are dumped into the city’s sewer system.
“They believed at the time that it would dilute with all the other stuff in the sewer system,” Smith said.
That wasn’t the case.
The chemical was disposed at 7:30 a.m. and detected at Willow Lake at 6 p.m. Wednesday, Smith said.
“We’re very sorry that the sodium bisulfite had an impact on Willow Lake’s biological processes,” he said.
“This is definitely not something that we’ll do again.”
Contact reporter Rachel Alexander: [email protected] or 503-575-1241.
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Rachel Alexander is Salem Reporter’s managing editor. She joined Salem Reporter when it was founded in 2018 and covers city news, education, nonprofits and a little bit of everything else. She’s been a journalist in Oregon and Washington for a decade. Outside of work, she’s a skater and board member with Salem’s Cherry City Roller Derby and can often be found with her nose buried in a book.
