32609 North Fish Lake Road
Round Lake,IL 60073
208 acres
6:30 am–sunset, daily.

Marl Flat

This scenic preserve is part of an Advance Identification (ADID) wetland complex because of its high quality wildlife habitat and native plant communities in wetlands around the lake. 

While there are no preserve trails here, Marl Flat does provide trailhead parking for our regional Millennium Trail system. Today, 33 miles of the Millennium Trail are currently open to hikers, bicyclists and cross-country skiers. An 11-mile section from Lakewood north to Singing Hills is also open to equestrians. The 1-mile paved section of Millennium Trail that runs through Marl Flat is open for hiking, biking, hiking and cross-country skiing. Please keep dogs leashed and on trails at all times, and pick up after them. Learn about our Off-Leash Dog Areas (permit required). Horses are not permitted. 

The preserve also has benches and an information kiosk.

No Fishing or Lake Access

The preserve's lake frontage along Fish Lake is a very sensitive natural resource area. As a condition of the land's purchase, public access to Fish Lake, including fishing, is not permitted.



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More About This Preserve

The Natural Scene

Marl Flat was named after a rare geological feature found at the preserve. Marl flats are distinct features of a fen, which is a type of wetland. These areas have flat soils that are high in minerals and calcium cabonates derived from alkaline groundwater.

Other natural features of the preserve include an interior pond and rolling hills that offer beautiful views. The lake and wetlands are used by a wide variety of waterfowl including black terns and yellow-headed blackbirds. It also features woodlands dominated by bur oaks and wetlands. Proper restoration is helping to revitalize the woodlands and enhance wildlife habitat throughout the preserve.

The preserve boundary has extensive frontage on Fish Lake Road, which will help maintain the scenic quality of this country-like road.


Funds from the voter-approved 2008 referendum helped create Marl Flat and provide for sections of the Millennium Trail in western Lake County.

We also received grants from the Illinois Open Land Trust Program to acquire land at Marl Flat, and from the federal Recreation Trails Program to help offset costs for trail and parking lot construction.


The entrance is on the east side of Fish Lake Road, north of Route 120 and south of Nippersink Road.

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