ILLINOIS RIVER DRAINAGE BASIN. 497 



to be about 29,000 square miles. An estimate made by L. E. Cooley, of 

 the Chicago Drainage Commission, reduces it to 27,914 square miles. The 

 area in each of the three States is estimated by Greenleaf to be as follows: 

 Illinois, 24,726 square miles; Wisconsin, 1,080 square miles; Indiana, 3,207 

 square miles. The drainage areas of the tributaries given in order from 

 source to mouth, as estimated b} r Cooley, are as follows: 1 



Drainage areas of tributaries of Illinois River. 



Square 

 miles. 



Des Plaines River 2 392 



Kankakee River 5 143 



Aux Sable Creek 218 



Mazon Creek 540 



Fox River 2 700 



Covel Creek 100 



Vermilion River 1 317 



Pecumsaugum Creek and Little Vermilion River 165 



Bureau Creek 4g0 



Sandy Creek 447 



Crow Creek ("east) 226 



Senackwine Creek (south) 132 



Kiekapoo Creek _ 310 



Mackinaw River 1 217 



Copperas Creek 151 



Quiver River 220 



Spoon River 1 379 



Sangamon River 5 370 



Sugar Creek _ IgO 



Crooked Creek 1 335 



Indian Creek 290 



McKees Creek 472 



Mauvaise Terre Creek 275 



Big Sandy Creek, etc _ 525 



Macoupin Creek 985 



'fota 1 26,303 



Total area of Illinois watershed 27 914 



Area of small tributaries and slopes 1 611 



Of the 27 tributaries included in the above table, it will be observed 

 that 13 carry 23,699 square miles, or about 85 per cent, of the drainage of 

 the Illinois Basin. There are, in addition to the tributaries above given, 

 20 more which are sufficiently large to have received names, but which 

 have a combined drainage area of only 1,300 square miles. The remaining 

 300 square miles are comprised in the slopes of the Illinois River Valley 

 and the insignificant tributaries. 



' Rept. Illinois State Board of Health, 1889, p. 

 MON XXXVIII 32 



