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Lake Information


Acreage: 53

Recreational Amenities

Boat Fishing? Unlimited HP, No Wake

Boat Ramps? Yes

Boat Rental? No

Skiing? No

Swimming? No

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There are no zebra mussels in this lake.

Lake Status Summary  ( Full PDF Report )

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Fish Status



The Spring 2023 electrofishing survey resulted in a total of 60 Bluegill collected ranging from 50 mm 2 in to 195 mm 7.7 in, with 53 of those fish > Stock size 3.0 in. Average length was 4.9 in. Like Largemouth Bass, Bluegill CPUE also dramatically increased from the Spring 2021 survey (again, likely due to focusing sampling in the Northeast finger). While the PSD remained the same, the number of Stock size and larger fish declined. Body condition was quite good for all size groups.



Unlike other waterbodies within the Mazonia complex, Monster Lake does not receive Channel Catfish from the State Hatchery System. The population is sustained through natural reproduction and/or fish migration from connected creeks. Electrofishing is not typically used to evaluate Channel Catfish populations, and as such this survey does not provide a good assessment of the fishery. Site Regulation: 6 Fish Daily Harvest Limit.



The Spring 2023 electrofishing survey resulted in a one Black Crappie collected measuring 7.7 in. Electrofishing is not a standard gear for evaluating Crappie populations and Fall trap netting is typically conducted to understand these fisheries. Site Regulation: 10 Fish Daily Harvest Limit.



Flathead catfish are present in Monster Lake and have been sampled in low number in IDNR surveys. None were collected in the Spring 2023 electrofishing survey.



The Spring 2023 electrofishing survey resulted in a total of 73 Largemouth Bass collected ranging from 2.8 in to 18.9 in, with 54 of those fish > 8.0 in. Average length was 11.1 in. Largemouth Bass catch rate dramatically improved, mostly due to the focus of sampling in the Northeast finger. Size structure remained similar though the PSD-P increased by 6 points. Body condition remains good. Length frequency distribution indicates that natural reproduction and survival is taking place with a good number of Sub-Stock fish collected. Site Regulation: 15-inch Minimum Length Limit (3 Fish Daily Harvest Limit).



The Walleye stocking program was initiated in 2016 and annual stockings are ongoing. The fishery is still in its infancy. Site Regulation: 14-inch Minimum Length Limit and a 18 – 24-inch Protected Slot Limit (4 Fish Daily Harvest Limit [One Over 24 inches]).

Location: Monster Lake is located within the Mazonia State Fish and Wildlife Area South Unit, 2 miles northeast of South Wilmington in Kankakee County off West 5000 Road.

Description: Monster Lake is a large impoundment, covering 52.9 surface acres with depths to 60 feet. Siltation and nutrient loading have resulted due to Granary Creek being routed through the lake (Monster Lake acts somewhat as a flood control reservoir). This connection to the stream, which is a tributary of the Mazon River, has diversified the fishery. Some opportunity for shore fishing exists and a primitive gravel ramp serves as boat access. See “Additional Lake Information” below for important site information.

History and Status of the Sport Fishery: The sport fishery is evaluated through routine, periodic fish community and targeted surveys utilizing electrofishing, trap nets, and other gears as appropriate. The lake is a backup brood source for the Kankakee River Walleye collection and receives Kankakee River strain fish on an annual basis.

No special mercury advisory or other contaminant-related consumption advisories pertain. However, the statewide methylmercury advisory for sensitive populations is in effect (one meal per week of predatory sportfish for the most sensitive populations).

Additional Lake Information: Swimming is prohibited. Gasoline motors (unlimited horsepower) are permitted on Monster Lake with a no wake regulation in effect. Unlike other Mazonia waterbodies, Monster Lake is open year-round to angling. Statewide fishing regulations apply.

Additional Site-Specific Fishing Regulations:
All Fish: 2 Pole and Line Only
Channel Catfish: 6 Fish Daily Harvest Limit
Black, White, or Hybrid Crappie: 10 Fish Daily Harvest Limit
Large or Smallmouth Bass: 15-inch Minimum Length Limit (3 Fish Daily Harvest Limit)
Walleye, Sauger, or Hybrid Walleye: 14-inch Minimum Length Limit and a 18 – 24-inch Protected Slot Limit (4 Fish Daily Harvest Limit [One Over 24 inches])

Contact Information:
Mazonia/Braidwood State Fish & Wildlife Area
IDNR Fisheries Biologist, Seth Love