Installation of new lock and dam miter gate; photograph taken in 2025 at Lock and Dam 7, La Crescent, Minnesota.
Purpose
Locks and Dams 2 through 10 have used the same miter gates since their construction in the 1930s. Over time, the gates have been damaged and distressed, leading to serviceability and safety issues. This project will replace the gates and upgrade the anchorage systems, increasing navigational longevity and operational readiness while decreasing repair costs and downtime due to maintenance or failure.
Location
Upper Mississippi Locks and Dams 2 through 10.
Description
To allow watercraft to pass through stretches of river of various depths, Congress authorized a series of locks and dams along the Mississippi River. Miter gates and the anchorages upon which they rest are an integral part of those locks.
Miter gates are comprised of two leaves that provide a closure at one end of a lock at a “miter,” or angle. Each lock has a set upstream and downstream miter gate. In coordination with other systems, these gates allow water levels within the lock to be controlled.
Status
Two U.S. Army Corps of Engineers (USACE) districts — St. Paul and Rock Island — have been collaborating to design and install new miter gates for the locks and dams of the Upper Mississippi River. To comply with modern design codes and best practices, the new miter gates are significantly heavier than the originals. Thus, USACE is also upgrading the miter gate anchorages and pin plates, which act as the hinges upon which the miter gates rotate.
Maintenance and Repair teams from both the St. Paul and Rock Island Districts installed the new Lock and Dam 6 and 7 gates in summer 2025.
New miter gates for Locks and Dams 3, 4, and 9 are in fabrication by G&G Steel of Russellville, Alabama. The Lock and Dam 9 gates are scheduled to be installed in summer 2026. The new Lock and Dam 3 miter gates are scheduled for installation in summer 2028, and the Lock and Dam 4 gates are scheduled for installation in summer 2029.
St. Paul District engineers have completed designing new miter gates for Lock and Dam 5. USACE will advertise the Lock and Dam 5 miter gate fabrication contract in the future according to the operations division’s budget priorities.
Authority
Congress authorized the Upper Mississippi River 9-Foot Channel Navigation Project as part of the River and Harbor Act approved July 3, 1930.
Funding
Miter gate replacement design and construction at the locks and dams are 100% federally funded.
Fiscal year 2025
Lock and Dam 6 and 7 gate installations $2,500,000
Lock and Dam 7 and 9 anchorage upgrades $3,000,000
Fiscal year 2026
Lock and Dam 9 pin plate upgrade $1,500,000
Lock and Dam 9 gate installation $1,250,000
Lock and Dam 5 gate fabrication award $12,500,000