Rotten-Egg Stench Near Thornton Reservoir Has Residents Shutting Windows and Skipping Cookouts

A smell residents describe as rotten eggs, decaying animals and stale garbage has been settling over Thornton this month, driven by heavy rain and heat that have pushed the village's stormwater reservoir close to capacity.

The Thornton reservoir sat at 89% full as of Thursday afternoon, according to the Metropolitan Water Reclamation District, down from a record 94% reached earlier in the week after last weekend's storms dumped water into the system. That drop eased worries about flooding, but residents say it did nothing to clear the air.

"It's like rotten eggs, or food or any type of animal that's been in the sun too long," said Pamela Price, who has lived near the reservoir for 27 years. Price said she has learned to plan her life around the smell during rainy stretches. "We're not going to have any outside activities. We're not going to invite any friends over," she said.

Other residents reached for similarly grim comparisons. Nancy Hammer, a longtime resident, described the odor as "decaying animals... dirt... stale, a garbage can." Janice Modory called it "putrid, foul, sour, moldy," and said pine trees planted near the reservoir to mask the smell haven't helped. Darren Krencgarz, who has lived in Thornton his entire life, said this stretch has been the worst he can remember. "I have noticed that last week when it was hot and humid, that is when it was really bad. I just rolled up my windows. No fresh air for me, I guess," he said.

Village Clerk Nikki Kitakis said the smell had been even more intense earlier in the spring, bad enough to disrupt youth sports. "All the parents, we're trying to enjoy our kids' T-ball game, and we have our hands over our face. Our shirts covering our noses. It was horrific," she said.

The reservoir has operated for 11 years and is believed to be the largest combined sewer reservoir in the world, part of a tunnel and storage system built to capture stormwater, cut down flooding and protect water quality across more than a dozen surrounding communities. The Metropolitan Water Reclamation District installed odor-control equipment when the facility opened, including aerators and sprayers, but Kitakis said those systems only partially work.

A district spokesperson said crews have been monitoring conditions and patrolling the area, but that as of Thursday morning, staff had not detected odors at the reservoir tied to the recent rainfall. "Without the reservoir, last week's significant rainfall could have resulted in increased flooding and other serious impacts," the district said in a statement. "We understand that unintended consequences, including odor concerns, can occur, and we continue to work to address them."

That explanation offers little comfort to residents who say they've been raising the same complaints for years. Kitakis said the village feels its concerns were never fully weighed when the reservoir was built. "I don't feel like we were taken into consideration when they decided to put the reservoir in. They didn't think about what it would do to the living conditions here," she said.

The district has set up a phone line, 800-332-3867, for residents to report odors, and Kitakis said the number is posted at Village Hall and printed in the village newsletter. The district also runs a citizen reporting app that lets residents submit odor complaints directly, saying every report gets investigated.

The reservoir remains close to capacity, and more rain is possible in the coming days. Kitakis said the village plans to keep pressing the district for a longer-term fix rather than temporary aerators and sprayers, and will raise the odor issue again at the district's next scheduled community meeting.