Vandals recently plugged a sewer manhole with tires, branches, concrete and metal, forcing 7,000 gallons a day of wastewater into Midway Creek and causing bacteria levels in the creek to rise.
"This is the worst one that has happened in Medford," said Cory Crebbin, the city's Public Works director. "It's a crime under federal law."
A city Public Works employee discovered the plugged manhole on May 8 while on a development inspection in the area. Crebbin said he isn't sure how long wastewater had been flowing into Midway in the Ford Drive area near Highway 62.
City workers fabricated their own tools to extricate the debris, avoiding the more perilous prospect of descending into the hole, he said.
The vandals stuffed materials into the manhole to block it intentionally, Crebbin said.
"To get that stuff down there is a project," he said.
A locking manhole cover was installed to prevent future vandalism. The manhole, which is not visible from the street, is located in a field on private property that is popular with local children.
A day after the blockage was cleared, bacteria levels returned to normal in Midway, Crebbin said.
The state Department of Environmental Quality and federal officials were both notified about the sewage spill.
City Manager Eric Swanson said the vandalism appeared to be the result of kids with too much time on their hands.
"It's a serious thing when you back up a sewer manhole," he said.
Councilor John Michaels said, "Just how sad is your life if you've got to be throwing stuff down a manhole."
The Public Works Department plans to identify other manhole covers in the city that aren't readily visible from the street, and the city may install more locking lids to prevent vandalism.
Andy Ullrich, compliance engineer with DEQ, said the city notified his department after it discovered the vandalism. He said the city would not be fined for the sewage discharge.
"In this case, since it is clearly vandalism, we will not be taking any further action," he said.
Reach reporter Damian Mann at 541-776-4476 or firstname.lastname@example.org.