Chicago's Deep Tunnel anti-flooding system nearly full after days of heavy rain

Key Points:

• Chicago’s Deep Tunnel system, designed to manage floodwaters through over 100 miles of tunnels and three reservoirs, is nearly full for the first time in history following heavy rainfall.
• The Thornton reservoir reached 94% capacity and the McCook reservoir is completely full, together holding 11 billion gallons of water, while the smaller Majewski reservoir remains under 3% capacity.
• Eleven suburban communities face river flooding threats due to the system’s capacity being nearly maxed out, and Chicago experienced sewer overflows into the Chicago River over the past three days.
• Experts attribute the flooding risk to both intense short-term downpours and cumulative steady rainfall over recent months, emphasizing that Deep Tunnel alone is insufficient to prevent flooding and advocating for more greenspace and new water storage solutions.
• Deep Tunnel remains incomplete, with an expansion of the McCook reservoir planned for completion by 2032; treated water from the reservoirs is eventually released into waterways flowing to the Mississippi River and Gulf of Mexico.