Stratton Lock and Dam lock capacity and water level control improvements (Illinois)

Project Summary

The Stratton Lock and Dam in McHenry, Illinois, is the lifeblood of the Chain O'Lakes. It helps move approximately 24,000 recreational boats from the upper Fox River to the lower Fox River in Algonquin, Illinois, and back again. Its gates push water south when the Chain O’Lakes is full, while holding water during the hot summer months.

Officials with the Illinois Department of Natural Resources (IDNR) found the gates were showing their age from deterioration of the concrete structure and obsolete equipment conditions, plus the boat lock was antiquated and lacked the capacity to serve the boats on the busy waterway.  


Improving lock capacity and water control were the key goals for Hanson’s study of the lock and dam structure on the upper Fox River. IDNR hired Hanson in 2011 to provide a Phase I pre-design report to review and summarize previous engineering analyses regarding improvements and alternatives. The project also included the remote control and monitoring of the Obermeyer gate at Algonquin.

About Stratton Lock

Stratton Lock, constructed in 1960, is 22 feet wide by 62 feet long with two miter gates. The sluice gate structure was constructed in 1939 and consists of five 13.75-foot-wide vertical lift gates, along with the adjacent Obermeyer gate on the fixed crest dam. The gates provide water control on the Fox River for the surrounding prime residential and environmentally sensitive areas, as well as water supply to downstream communities.

How Hanson Helped

Hanson’s team reviewed prior studies related to the lock and dam condition and to increasing the lock capacity. It evaluated various alternatives, including lock extension and a new parallel lock, with respect to constructability, construction costs operations and maintenance (O&M), redundancy and safety.

Team members evaluated the existing conditions at the lock and dam. They also developed gate structure replacement alternatives.

Hanson provided engineering and design services for the project, which included analyses; design; preparation of plans; specifications; permitting; construction cost estimating; and O&M manuals.

  • Larger Lock: Because boat sizes have increased since the original lock was built in 1960, only four large boats could safely pass through the lock at once. This caused significant delays. The Hanson team's design improved the lock, doubling its length and capacity. The redesigned, larger lock can now accommodate eight larger boats at one time.

  • A new water-level control structure uses torque-tube crest gates, replacing the outdated gate structure. The new gate structure uses three hinged crest gates to replace the sluice gate structure. The new gate design allows IDNR to better control the upstream pool elevation of the Fox River.

  • Innovative designs: A supplemental filling port with a diffuser raises the water level and keeps the level calm during filling, which is safer for boats. A bypass pipe in the gate structure that guarantees 320 cubic feet of water per second can pass the dam, meeting IDNR’s requirement to supply water to downstream communities.

Hanson has provided support to IDNR through bidding and construction.


2023: Public Works Project of the Year Award from the American Public Works Association

2022: Outstanding Civil Engineering Achievement Award from the American Society of Civil Engineers’ (ASCE) Central Illinois Section (CIS).

"Your work at Stratton Lock and Dam is appreciated. It was my honor to work with the many talented staff at Hanson Professional Services." — Arlan Juhl, Former Director, Illinois Department of Natural Resources, Office of Water Resources