Work on the Deep Tunnel caused a super stinky situation along the North Shore Channel this week. View Full Caption Flickr/Dodo-Bird

LINCOLN SQUARE — Folks who live, work or play along the Chicago River have grown accustomed to malodorous wafts of vapor emanating from Deep Tunnel sewer vents, but the stench earlier this week reached unusual levels of intensity, with residents from Irving Park to North Park crying foul.

Some thought skunk, others thought their pet had an "accident" in the house.

Patty Wetli says neighbors took to social media to complain:

"I'm going to need a gas mask for my morning run," one person posted on Facebook.

The mystery has been solved.

On Tuesday morning — when most people began noticing the acrid smell — the Metropolitan Water Reclamation District shut down its Skokie plant for construction of a disinfection facility. The plant's flow — a mix of sewage and stormwater — was diverted to the Deep Tunnel at Howard Street, resulting in odors along the North Shore Channel, water district spokeswoman Allison Fore said.