Thornton Reservoir

Chicago District
Published Jan. 10, 2024

Additional details can be found at

Project Description and Background

The Thornton Reservoir significantly reduces overland and basement flooding by protecting 35,090 structures. It also improves the quality of area waterways by significantly reducing the backflow of untreated sewage into Lake Michigan and by storing combined sewer overflow during floods before release to the Calumet wastewater treatment plant. The original 14,600 acre-feet reservoir was increased by 9,600 acre-feet to a total volume of 24,200 acre-feet (7.9 billion gallons) for the new “composite” reservoir.

The Non-Federal Sponsor completed the reservoir in 2015 and is eligible for reimbursement of the federal share.

Current Status

Using non-Federal funds, work included documentation of construction completed by the non-Federal sponsor. Reimbursement to the non-federal sponsor of $12,000,000 was completed using FY22 Work Plan funds.

If additional funds are provided, they would be used to continue reimbursement to the non-Federal sponsor for the federal share of the project.

The non-Federal sponsor completed final construction of the reservoir in 2022.

Project Authorization

Sec 3(a)(5) of the Water Resources Development Act of 1988, as amended