The recent near-overflow of the Thornton reservoir in Chicago has brought attention to the city's Deep Tunnel flood-control system, a massive operation that has been in the works for 50 years. This system, which includes over 100 miles of underground tunnels and three reservoirs, is designed to manage stormwater and sewage during heavy storms. Thornton, along with the McCook reservoir, has been slowly draining for days, with the water being pumped to sewage-treatment plants. The Thornton reservoir, in particular, has been a concern due to the putrid smell from the sewage, which has caused complaints from neighbors. The Metropolitan Water Reclamation District is spending $5 million on technology to reduce odors around the Thornton site, including carbon filters and a mist system. However, the district acknowledges that more must be done to mitigate flooding as extreme thunderstorms are intensifying and are predicted to get worse due to climate change. The Thornton reservoir is expected to take at least a month to drain completely, and the district is monitoring additional rainfall, incoming sewer flows, and treatment plant conditions to determine the speed of the drainage process. The Deep Tunnel system, officially known as the Tunnel and Reservoir Plan, is still being expanded, with a project to increase the size of the McCook reservoir by the end of 2032. Despite these efforts, government planners recognize the need for further measures to address the increasing frequency and intensity of extreme thunderstorms, which pose a significant challenge to the city's flood-control infrastructure.
