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Lake Information

County: McHenry

Acreage: 45

Recreational Amenities

Boat Fishing? Carry-in only, Electric

Boat Ramps? Yes

Boat Rental? Yes

Skiing? No

Swimming? No

Picnicking? Yes

Camping? No

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Maps are not intended for navigation.

There are no zebra mussels in this lake.

Lake Status Summary  ( Full PDF Report )

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Fish Status



Bluegill catch rate was low in the last survey. While it has been as high as 80 fish per hour, the 2018 catch rate was only 54 fish per hour. Bluegill ranged in length from 3.6 to 7.2 inches, with the average fish measuring 5.4 inches. Other panfish species in Defiance Lake include; black crappie, green sunfish, pumpkinseed and warmouth, and yellow perch.



Non-vulnerable sized (8-12 inches) channel catfish are stocked annually in Defiance Lake. No channel catfish were sampled in the 2018 survey. Previous surveys have reported channel catfish greater than 20 inches in Defiance.



Largemouth bass have not been abundant during any of the last four surveys in the past 11 years. Three bass less were caught in the 2018 survey. None were over 14 inches.



A spring netting survey took place in March of 2018. The northern pike catch rate was over six fish per net night. Abundance, based on catch rate, was higher in 2018 than in the previous three surveys. The pike in the survey ranged in length from 17.6 to 30.5 fish, with the largest weighing 5.5 pounds. Unfortunately, the hatchery system stopped producing northern pike in 2015. Future surveys will take place to determine if natural reproduction can maintain the pike in Defiance.

Location: Defiance Lake is a natural lake in Moraine Hills State Park, which is located three miles south of McHenry off of River Road between Illinois Route 120 and 176 in McHenry County.

Description: Defiance Lake is one of a handful of natural glacial lakes in Illinois that has remained relatively undeveloped. Its maximum depth is 18 feet. The lake stays fairly clear for most of the year, but vegetation does become quite thick. Treatment of vegetation is not an option due to threatened plant species. There is no boat launch at the lake, but carry-in boats/canoes/kayaks are allowed. Rental boats are available. Bank fishing is prohibited due to hazardous peat soils that surround the lake, except for designated piers along the boardwalk.

History and Status of the Sport Fishery: Defiance Lake is stocked annually with largemouth bass and channel catfish. The lake is surveyed by IDNR every two years and supplemental sampling for northern pike occurs when conditions allow. Defiance Lake is difficult to sample effectively with electrofishing gear as the vegetation becomes very thick early in the year. Due to this reason, catch rates for most species are low. While abundance may be underestimated, species richness seems to be pretty consistent throughout the years. Defiance Lake should provide something for the angler who wants to catch something other than bass and bluegill as overall, it is a year-round productive and diverse lake that offers a chance to see some uncommon fish species: captured in 2018 were brown bullhead, bowfin, yellow perch, grass pickerel, common carp and pumpkinseed. Previous surveys have shown black crappie, black bullhead, brook silverside, central mudminnow, golden shiner, green sunfish, lake chubsucker, longnose gar, warmouth and yellow bullhead to be present in Defiance Lake.

Fish attractors were installed and fish have been observed using them. Three attractors have been placed and can be seen on the map here:

Additional Lake Information: Anglers may use no more than two lines or poles when fishing at Defiance Lake. Rental boats are available. Carry-in canoes and kayaks may be launched at the boat ramp located behind the office. Bank fishing is prohibited due to hazardous peat soils that surround the lake, except for designated piers along the boardwalk. Note that piers quickly become surrounded by dense aquatic vegetation during summer months and vegetation treatment is not an option at this lake due to the presence of rare and sensitive plant species. Electric trolling motors are allowed.

Contact Information:
Moraine Hills State Park
IDNR Fisheries Biologist, Andy Plauck
815-675-2386 ext. 214