Tuesday, January 31st, 2023
Tuesday, January 31st, 2023

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Illinois Woods & Waters – Heidecke Lake, Grundy County

Heidecke anglers eager for April 1 opener


By Ralph Loos


Heidecke Lake opens for the new season on April 1 – and the little question is how high water will affect fishing.


The big question: will the fish be hungry?


The 1,955-acre lake is located in Grundy County approximately 1 mile south and 8 miles east of Morris, between Illinois Route 47 and Interstate 55 on Lorenzo/Pine Bluff Road.


About 75% of the shoreline comprised of rock rip-­rapped dikes. 


Formerly known as Collins Lake, Heidecke was impounded in the late 1970s.  Its waters have been used to cool down the Collins Station power plant that was owned and operated by Midwest Generation.  A few years back the plant was shut down and dismantled piece by piece.  The lake is now like any other natural lake in northern Illinois. Many anglers still call it one of northern Illinois’ cooling lakes.


Heidecke Lake has pure and hybrid stripers, largemouth and smallmouth bass, catfish, walleye, bluegills, crappie and yellow bass. And don’t forget the muskie. Heidecke has them, too, and some big ones.


Traditionally Heidecke produces some decent fishing in the spring, even in the cool conditions of April.


  Numbers may not be there but the quality will be good.  As the water warms, it just gets better.


 Heidecke receives annual stockings of walleye, black crappie and hybrid striped bass. Pure muskellunge are stocked every third year. 


Following are brief descriptions of the major sportfish species in this water body, as provided by the most recent surveys of the lake by DNR fisheries biologists.


 Bass: The collection of smallmouth bass was down slightly from the previous  survey  but  total  numbers  remained  high  and  continue  to  rival  those  large  collections  of the late 1990s and early 2000s. Smaller fish remain elusive in these surveys. 


The large contingent of fish falling within the protected slot range has caused an increase in competition for forage and likely, slowed growth. 


Round  gobies, which were collected in 2014, were absent     from more recent surveys and it is possible this is due in part to predation on these fish by a fairly robust smallmouth bass population.  


The collection of largemouth bass continues to decline as evident by the fact that the recent collection fell by 38% from the previous survey. The survey rates as the fewest largemouth bass ever collected           in a major DNR fall survey. 


Length frequency distribution is very sporadic with some consistency up to approximately  10  inches,  after  which  point  numbers  decline.  


“The number of largemouth bass 12 inches and larger has been declining for several years,” DNR reported. “This is despite a protected  slot limit of 12  to  18  inches. The largemouth bass population at Heidecke has been poor for the last 10-plus years.” 


Walleyes: Following the record-­setting years of 2012 and 2014, the walleye collection declined somewhat in  subsequent years,  although  catch  rates  were  not  far  from  the  long-­term  averages.  


Size  distribution was fairly consistent, which indicates good survival and recruitment of stocked fish. Walleye stockings have been conducted annually, except for 2010, with stockings generally averaging 35 fish per acre. Smaller walleye were not well represented in this survey and 83% were legal size. The average size walleye collected was  19.5 inches, while nearly 8% of the collection exceeded 25 inches.


Hybrid striped bass: Following an extremely poor showing in the 2014 survey, the striped bass hybrid collection increased dramatically. All population indices exceeded the previous survey as well as long-term averages.  


The  majority  of  the  hybrid  striped  bass  collected exceeded  17  inches, which should help to reduce angling mortality somewhat. 


Muskies: Collection numbers in the most recent spring trap netting survey declined somewhat but this belies the fact that Heidecke Lake supports a very strong muskellunge population. Larger fish are becoming more prevalent in spring surveys with fish commonly exceeding 30 pounds. 


Several fish were also collected, the largest measuring 45 inches.


Crappies: Poorly represented in the fall survey, spring trap netting provided a larger collection with fish up to 11 inches collected. Despite the poor returns in DNR surveys, angler reports indicate excellent catches of crappie during recent seasons.


Channel catfish: Since 2008, there has been little evidence of reproduction and/or recruitment for channel catfish. The average size for channel catfish collected in DNR surveys has steadily increased and in the most recent survey average size catfish collected reached an all-­time high, surpassing the long-­term average by nearly 3 inches.


Other species:  Heidecke Lake is maintained by periodically pumping water from the Illinois River. As a result, the lake supports a variety of fish species which include sunfish (bluegill and green  sunfish), common carp, bullheads, freshwater drum and others. 

Heidecke Lake

Heidecke Lake is supported by a thriving gizzard shad forage base as well as various other minnow species.

Nearest town ……………Morris

Surface area ……. 1,955 acres

Average depth …..……… 9 feet

Shoreline ……………… 17 miles


Species present

Bluegills, largemouth bass, smallmouth bass, channel catfish, sunfish, hybrid striped bass, walleyes, muskies, freshwater drum, carp, bullheads


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