310 



Illinois Natlrai. History Survky Bui.i.utin 



Vol. 28, Art. 2 



Table 1. — Water discharge records taken at five gaging stations in Champaign County 

 (U. S. Geological Survey, 1953-1960). 



Stream 



Sangamon 



Salt Fork 



Kaskaskia 



Boneyard 



West Branch 



Location 



OF 



Station 



Near Mahomet 

 Near Homer 

 Near Boiid\iIle 

 Near Urbaiia 

 Near Urbana 



WATKRSHF.n, 



Square 

 Mii.es 



356.0 

 344.0 



12.3 

 4.6 



71.4 



Annual 



Average 



Discharge 



(C.F.S.) 



249.00 



243.00 



8.05 



4.62 



50.40 



Years 



OF 



Records 



1948-1957 

 1944-1957 

 1949-1957 

 1948-1957 

 1936-1957 



>ard. The lowest discharjie per acre was 

 for the Kaskaskia drainaiic, which is en- 

 tirely farmland, and the hi<:;hest dischar<j;e 

 was for the Boneyard drainaj^e, which is 

 almost entirely urban, lying within Cham- 

 paif2;n-Urbana. 



The records on the Sant^amon River 

 taken near Monticello are of special value 

 in that they show chanjjes in stream dis- 

 charge over a long period. Although the 

 gaging station is about 10 miles outside 

 Champaign Count\ , it records the runoff 

 from one-quarter of the county. Records 

 are nearly complete back to 1908. They 

 show that annual average discharge fell 

 below 200 c.f.s. only once during the two 

 decades before the Thompson & Hunt 

 study of 1928, but fell below this level 

 eight times in the three decades since. The 

 low discharges in recent years indicate 

 the reduced water-holding capacity of 

 soils of the watershed. I he river now re- 

 sponds quickly to precipitation or drought, 

 whereas it had a more nearlv constant 

 flow before 1^28. 



The minimum discharge of a stream 

 has great significance to fish distribution. 

 Before the Thompson & Hunt study, 

 there was no record of the Sangamon 

 River discharge dropping as low as 1.0 

 c.f.s. but it reached 1.0 c.f.s. or lower five 

 times in the three following decades. As 

 might be e.xpected, there is a high correla- 

 tion between precipitation and water dis- 

 charge of streams in an area. There is, of 

 course, a variable time lag between pre- 

 cipitation and discharge. 



Draining and Dredging. — Because 

 of the original marshy character of Cham- 

 paign County, much draining, dredging, 

 and straightening of waterways has been 

 necessary to prepare the land for agri- 

 culture. 



The Illinois Farm Drainage Act of 

 1879 encouraged the formation of drain- 

 age districts and enabled farmers to par- 

 ticipate in the installation of drainage 

 systems to serve large areas. Drainage 

 proceeded rapidly during the following 

 two decades, and, by the turn of the cen- 

 tury, when Forbes & Richardson made 

 the first extensive fish collections in the 

 area, 36 per cent of the county's 632,415 

 acres had drainage improveir.ents, table 2. 



The number of acres in drainage dis- 

 tricts almost doubled between 1900 and 

 1910, with 190,205 additional acres (30 

 per cent of the county) receiving drain- 

 age improvements. In the decades since 

 1910, the amount of new land drained 

 has declined, table 2. The acreage of land 

 placed in drainage districts in the three 

 decades between 1930 and 1960 amounted 



Table 2. — Acres of land in Champaign 

 County placed in drainage districts during each 

 period since about 1880 and the per cent of 

 the county (632,415 total acres) with drainage 

 improvements by the end of each decade. In- 

 formation from the Federal Land Bank of St. 

 Louis and Champaign County records. 



*In 1921-1930, 3,060 previously unrecorded acres that 

 had received drainage improvements prior to 1927 (dates 

 iinknoH-iO were included in the acreage total for this 

 period, column two, and takeji into account in the per- 

 centage figures for this and later periods, column three. 



