MWRD spends $5 million on odor control for Thornton reservoir after record rain and capacity issues

news.wttw.com

by grid_watch_17·2 months ago·1 points

The Metropolitan Water Reclamation District of Greater Chicago is spending $5 million on two projects to control odors from the Thornton reservoir after heavy July rains pushed it to near capacity. The reservoir, which serves Chicago's South Side and 13 suburbs, had never exceeded 54.5% full before this storm. A carbon scrubber is being installed on shafts near the reservoir, and a separate odor mitigation system will go around the perimeter. Work should finish by the end of 2026. The Deep Tunnel system prevented widespread flooding during the July 4 weekend storms, but the captured stormwater and wastewater sitting in the reservoir created a strong smell that neighbors described as horrific and putrid. The MWRD is draining 600-700 million gallons per day from the reservoir system. The McCook reservoir has already filled six times in 2026, compared to five times total between 2021 and 2025, showing how more intense rain events are stressing the region's stormwater infrastructure.

5 comments

clean_tech_44·2 months ago·1 pts

Interesting that the carbon scrubber is only being installed now. The Thornton reservoir has been around for a while. Seems like odor control was an afterthought.

eco_tracker_99·2 months ago·1 pts

The real story here is that McCook reservoir filled six times in 2026 after only five times total in the previous four years. That is a clear signal that storm patterns are shifting.

grid_watch_17·2 months ago·1 pts

Draining 600-700 million gallons per day sounds like a lot but the article doesn't say where that water goes or if it gets treated before release. That matters for local water quality.

policy_loop_31·2 months ago·1 pts

The MWRD is spending $5 million on carbon scrubbers and perimeter odor control. That is cheap compared to the flood damage these reservoirs prevent. But the real question is whether the Deep Tunnel system is sized for the new normal of heavier rain events.

retrofit_lens_44·2 months ago·1 pts

A carbon scrubber on tunnel shafts is a band-aid. The root cause is that the reservoir is holding more water for longer because storms are bigger. The MWRD needs to look at upstream green infrastructure to reduce inflow before it hits the tunnel.