$1.34 million in federal funding will allow long-sought Sylvan Lake dam upgrade to proceed

Long-sought modifications and improvements to a nearly century-old earthen dam in Fremont Township will be made possible through a $1.34 million federal grant.

Sponsored by the Lake County Stormwater Management Commission, money to proceed was secured by U.S. Rep. Lauren Underwood of Naperville through a new initiative allowing her to request funding for projects to address pressing needs throughout northern Illinois.

The money resolves a yearslong effort to upgrade the dam and provide protection for hundreds of nearby homes. The dam serves the Sylvan Lake neighborhood off Midlothian Road near Mundelein and is well past its useful life, officials contend.

For years, Lake County officials sought to address issues to avoid potential flooding to roads and damage to utility lines should the dam fail. Yet, despite spending more than $400,000 for engineering and permits, finding money to build the project has been a dilemma for the Fremont Township Highway Department.

"It's an incredible relief to know we'll have this need met," said Alicia Dodd, Fremont Township highway commissioner.

The highway department owns Sylvan Dam and North Highland Drive, a single-lane entry to the subdivision atop the dam as well as a triangular-shaped property to the east where the original 93-year old concrete culvert and spillway discharge into a small creek.

If the dam fails, water would flood Highland Drive as well as well-traveled Midlothian Road and the entry road to 137 homes to the south in Long Grove, according to Dodd.

Dam upgrades also would protect nearly 500 homes that would be affected if a sanitary sewer line that runs over the spillway ruptured, according to the stormwater management commission. The resulting spill in the waterway would require "massive cleanup and repair," Dodd added.

Upgrades include a valve system to better deal with future extreme rainfall events and flooding.

"Lake County experienced countywide record flooding in 2017 and erosion damage to this infrastructure has accelerated as increased precipitation and climate change impacts the region," the commission said when announcing the grant.

Key aspects of the project call for the dam to be compacted and raised a foot, the deteriorating culvert removed and utility lines permanently relocated.

Once surrounded by farmland, increased runoff also has become a factor, said Dodd, who inspects the dam area at least once a week.

"It's another example of development causing problems for what was existing," she said. "I want people to understand why this is important."

Dodd was appointed in 2019 and elected in 2021. Repairing the dam had been a concern of the department for years before her tenure. But it had not been submitted or classified with the state.

"The dam has reached its useful life," Dodd said. "The spillway itself is compromised and no changes could be made without it (the dam) being a Class II (designation), so we're at an impasse."

Repairs can't be made until the dam meets the standards required by the Illinois Department of Natural Resources for a Class 11 category of dam. That designation is required because development downstream increases the potential for damage should the dam fail, Dodd said.

With an annual budget of $1.4 million and 35 miles of roads to maintain, funding the dam project would have been crippling to the highway department, Dodd said.

"This is above and beyond what we could do," she said. "I would have to put road paving on hold for three years."

Dodd approached stormwater management for funding assistance. Dam removals are eligible but dam modifications are not, said Kurt Woolford, the commission's executive director.

Underwood visited the site and championed the project when it was brought to her attention, he added.

The six-month project initially was anticipated to start this year but likely won't start until 2023 because of delays in federal funding approval.

To do the work, the 32-acre Sylvan Lake will be lowered by about 6 feet or half its current depth. Gas, sanitary sewer and a water line in the construction area will be relocated.

The deteriorating concrete culvert will be removed and replaced with a new system. From a vertical pipe at lake level, water will drop to a 42-inch diameter pipe and travel about 95 feet to the outlet, which will be reoriented to reduce erosion and lined with rock to dissipate water flow.

The spillway will be graded to have a less severe slope. Also, a 5-foot wide concrete walkway will be built on the lake side allowing pedestrians to cross the dam safely.