The Stratton Lock and Dam in McHenry will receive a $16.7 million facelift that officials say should significantly cut the time boaters wait to travel between the upper Fox River and Chain O' Lakes and the lower river in Algonquin.
However, officials said, the new gates will not help alleviate flooding on the recreational waterway, something nearby residents had hoped for since potential renovations to the aging dam were first mentioned in 2012.
"The only way to reduce flooding on the Chain O' Lakes and Fox River is to make the water disappear," said Rita Lee, the chief engineer of Studies Section for the Illinois Department of Natural Resources. "Until we create water storage somewhere, there is no real way to reduce flooding for everyone."
The IDNR announced Tuesday the renovation work will begin Nov. 1 at the lock and dam, which is just south of the River Road bridge over the Fox River in McHenry County.
Officials said some areas are being fenced off around the dam in preparation for construction, though some additional permits are needed before the actual work can begin.
Officials said the project will provide: A new sluice gate structure upstream to replace the aging equipment built in 1939; a new extended boat lock to double the capacity of boats entering and exiting the lock at one time; and a berm will be rebuilt on the west side of the river to fix soil erosion problems.
Construction will not interrupt water level control of the Chain or Fox River, and will not affect normal operation for about 17,000 boats that pass through the lock and dam annually, officials said.
"This is a good thing for the Chain and the Fox River," said Ron Barker, executive director of the Fox Waterway Agency in Fox Lake.
The dam was donated to the IDNR in 1923, after starting as a spillway in 1907. Sluice gates were added in 1939 after major flooding showed officials needed the ability to regulate water flow.
The gates are always a point of controversy on the Fox River because they control the amount of water released downstream. If too much is released too soon, the lower river floods; if not enough is released, the Chain washes out.
Officials initially reviewed whether water flows through the dam should be adjusted during renovations, the IDNR's Lee said. Officials decided the dam should maintain the same flows because "when trying benefit one side, you hurt another," she added
Once the new gates are fully operational after renovations are completed in November 2016, the existing gate structure will be removed.
A key benefit of the project is to the boat lock, which operates like a "water elevator" to lift and drop boats between differing water levels on the upper and lower river. If a boater wishes to travel from the lower river to the upper river, the boat pulls into the lock and water rises slowly until it meets the height of the upper river. The reverse happens and water is released for a boat traveling in the opposite direction, officials said.
Because boat sizes have steadily increased since the original lock was built in 1960, only four large boats can safely pass through the lock at one time, Barker said. The larger lock should be able to accommodate eight larger boats at one time, he said.
"It's really going to make for quicker movement for boaters through the locks," he said. "On busy days, boaters can wait between two and three hours to get through. This should reduce that."
The mechanical systems of the lock will also be rehabilitated during the project, IDNR officials said.
The lock and dam will not be open to visitors when construction begins. Boaters should be alert to construction zones near the lock and dam to ensure the safety of boaters and construction crews, officials said, and only limited fishing access will remain outside the construction fencing.
The project is being paid for through funding available for dam safety and improvement projects, officials said.