LAKE MANAGEMENT REPORTS 
2. FORK LAKE NEAR MOUNT ZION, ILLINOIS 
David H. Thompson and George W. Bennett 
Illinois Natural History Survey 
Fork Lake was built in 1920 by Mr. Paul S. Smith for waterfowl, hook-and-line 
fishing and other recreational uses, Since its establishment, the lake has been used 
by large numbers of waterfowl during their spring and fall migrations, As many as 
25,000 ducks have visited this pond during the course of a season, 
Soon after the lake was made, it was stocked with fish and for a few years 
furnished excellent catches of bass and other "fine" fish. Later, in spite of heavy 
stocking, hook-and—-line fishing became very poor, During the past year or two the 
lake appeared to be crowded with small black bullheads, Golden shiners and small 
sunfish were also known to be present. Occasional evidence was seen of large "rough" 
fish which would not take the hook, 
We recommended that all of these fish be removed and the lake restocked with. 
largemouth bass and bluegills, Since the lake could not be drained readily, the 
fish were poisoned, June, 1938, A complete census of the fish present was made at this 
time. This census is especially significant because, very few fish having been 
removed in recent years, it shows the carrying capacity of such waters for fish, 
After the fish were removed the water became clear, Within two weeks the lake was 
restocked with largemouth bass fry and adult bluegills, The bluegills spawned through- 
out the summer and their fry have been an important food for the bass, These bass have 
grown very rapidly and some of them should reach legal length by the time they are a 
year old, 
ACKNOWLEDGMENTS 
Mr. Smith furnished a great deal of the information. in this report and, together 
with Mr. Sam A, Parr of the Conservation Department and Dr. Donald F. Hansen of the 
Natural History Survey, helped in all stages of the work, When the census was made, 
we were assisted by a number of people from the Department of Zoology of the University 
of Illinois, Mr. Louis A. Krumholz of the Survey made the map, The view of the lake is 
from a photograph by Mr. James 8S. Ayars, editor for the Survey. The duck pictures were 
taken from a blind by Mr. Smith a number of years ago, 
DESCRIPTION OF THE LAKE 
Fork Lake was formed by throwing an earthen dam across a ravine, It is fed by 
surface drainage from about 60 acres, part farmland and part timber. The soil is a 
tight, light-colored clay loam, 
In June, 1938, at the time the accompanying map was made, the water surface of the 
lake was 5 inches below the crest of the spillway. The water area at that time was 1,38 
acres, The maximum depth was 9 feet. The average depth was 5,7 feet, and the capacity 
7.9 acre feet. According to Mr. Smith, there is now about 4 feet of silt in the lower 
end of the lake, 
The dam is 120 feet long, The spillway is 12 feet wide and 20 feet long, The 
water descends in four steps, the highest of which is 3 feet, The height of these 
steps is of some interest since it seems likely that, during freshets, carp and buffalo 
may have ascended the stream and jumped the spillway into the lake, The lake has not 
suffered extreme shrinkage during drought years. During the drought of 1950, the water 
level fell about 34 feet below the crest of the spillway. 
