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WHY ALL THE ‘SAVE ALLERTON PARK’ CRIES? 
A STATEMENT BY THE COMMITTEE ON ALLERTON PARK 
PART I 
1. What is Robert Allerton Park? 
On October 14, 1946, the late Robert Allerton gave “... the University 
(of Illinois) his beautiful country estate for educational and research 
purposes to be used as a forest, wildlife, and plant preserve, as an example 
of landscape gardening, and as a public park. This homestead includes an 
English-Georgian mansion, other buildings, and approximately 1,500 acres 
of garden park, and forest areas ... This is a magnificent gift to the 
University and to the general public.’ (Minutes of the Board of 
Trustees, 1946.) 
2. How is the Park maintained? 
An additional 3,775 acres of farmland was provided by Mr. Allerton with 
the stipulation that a portion of the income from this farmland be used to 
maintain and develop the 1,500 acre park near Monticello. (Danford, 
et al., 1951.) 
3. What is the present Oakley Dam project? 
There would be a dam and reservoir at the upstream end of Lake Decatur 
which would serve the following four functions: water supply for Decatur, 
fiood control, recreation, and water quality control in the Sangamon River 
below Decatur. (U.S. Corps of Engineers, 1967.) 
3a. What would be the reservoir’s water level and extent in Allerton Park? 
The so-called “permanent conservation pool’ water level would have an 
elevation of 636 feet above sea level. (U.S. Corps of Engineers, 1967.) 
This water level would cover about 600 acres of the 1,500-acre Allerton 
Park, to an average depth of 5 feet—the deepest being 8 feet. (D’Alba, 1967.) 
3b. Would the water level in the reservoir ever be below the permanent 
conservation pool level? 
Yes. Potable water for Decatur, water quality demands, and evaporation 
during dry summer periods would lower (“draw-down’”’) the water level. 
The drawdown normally would begin in late spring and reach a maximum 
in early fall. The Corps has calculated drawdown based upon 55 years of 
records on river flow at the Oakley site. (D’Alba, 1967.) The average 
maximum drawdown as cited by the Corps would be 5 feet. (D’Alba, 1967.) 
However, this figure is an annual average. The range of peak drawdowns 
would be from 0.4 feet to 15.5 feet. (D’Alba, 1967.) The effects of draw- 
downs on the lake is best illustrated by the fact that a 15 foot drawdown 
will decrease the length of the lake from 24 miles to 8 miles, leaving 
16 miles of exposed lake bottom. (Klimstra, et al., 1967.) 
3c. Would the water level in the reservoir ever be above the permanent 
conservation pool level? 
Yes. Because of the flood control aspect of the dam, as much as 193 addi- 
tional acres of Allerton Park would be flooded by as much as an 18 foot 
increase in the water level during periodic impoundment of flood water 
from heavy rains or melting snow. (Keith, 1967.) By altering 98 miles 
of the channel downstream, the Corps of Engineers anticipates that the 
