145 



Monthly Means of Gage-readings (in feet) below LaGrange Dam 



1883- 1899. 









(Basis of refe 



rence, 



low water of 1879.) 











Year 



Jan. 



Feb. 



Mar. 



April 



May 



June 



July 



Aug. 



Sept. 

 1.67 



Oct. 



Nov. 



Dec. 



Yearly 

 mean 



1883... 



7.41 11.36 



16.71 



12.77 



12.18 



13-04 



10.34 



5.62 



2.52 



6.89 



8.81 



9. 11 



1884. . . 



6.09 13.04 



14.17 



14.92 



11.22 



8.66 



6.42 



4.04 



2-74 



7.62 



6.01 



6.70 



8 



47 



1885... 



14.17 



12.06 



13-84 



14.20 



12.48 



7-99 



6.40 



4.72 



5.18 



5-69 



9-32 



8.15 



9 



S2 



1886. . . 



12.83 



13-77 



14.24 



13-79 



12.77 



9-31 



2.79 



1 -54 



1.68 



2-53 



2.12 



2.32 



7 



47 



1887... 



3-70 



12.71 



1364 



7-36 



3-75 



1.70 



0.72 



0.23 



0.24 



0.79 



0.83 



2.21 



3 



99 



1888... 



6.25 



7.62 



9.87 



12.01 



9.02 



10.78 



8.61 



3-93 



1 .21 



o-95 



1.70 



2.05 



6 



17 



1889*. . 



4-33 



3-So 



7.27 



5.78 



3-72 



9.48 



9.05 



4.00 



2.45 



0.92 



3-75 



5-43 



4 



98 



1890. . . 



10.22 



9.41 



8.92 



10.43 



9-39 



8.82 



6.83 



1-39 



1 . 11 



1.58 



1.86 



1 .92 



5 



96 



1891... 



2.21 



2.67 



6.06 



10.13 



9.00 



5.18 



3-56 



2. 16 



0.92 



0-32 



1.23 



2.83 



3 



86 



1892... 



3-42 



4.84 



6.69 12.70 



17.16 



15-97 



H -39 



5.84 



2.13 



1 .29 



1.69 



2.94 



7 



42 



1893.- • 



2.46 



8.31 



15.4413.74 



i5-«7 



12.00 



4.24 



0.68 



0.34 



1.28 



1 .09 



2.24 



6 



45 



1894... 



2.70 



4.19 



7-38j 6.28 



5.80 



3-24 



1.26 



o-57 



2.96 



1.56 



i-73 



2. 12 



3 



30 



1895... 



1.96 



2.70 



4.98) 4.05 



2.32 



o-73 



1.96 



i-55 



2.74 



0.86 



1.02 



4-99 



2 



49 



1896... 



10.06 



8.64 



8.921 6.61 



5.90 



7.09 



4-77 



7-59 



4-32 



5.28 



5.20 



4-85 



6 



60 



1897. : 



11.50 



10.95 



14.5015.40 



10.28 



4-99 



5-65 



1.80 



0.98 



0.86 



i-43 



1-93 



6 



67 



1898... 



4-55 



9.09 



13-iS 



16.33 



12.74 



12.8s 



S-44 



3-29 



3-96 



3-57 



6.75 



6.40 



8 



14 



1899... 



7.87 



7.87 



13-79 



11.58 



8.92 



8-93 



3-94 



2.28 



1.08 



1.23 



2-45 



3-19 



8 



09 



Means 























for 17 





























years. 



6.57 



8.40 



11. 15 



11.07 



9.56 



8.28 



5.67 



3.01 



2. 11 



2.28 



3-25 



4.07 



6.40 



*Dam practically completed in November of this year. 



accounts for much of this change. Records during a period of 

 abundant rainfall are necessary for an adequate discussion of 

 the problem. 



The foregoing tables give the monthly means and monthly 

 and yearly averages at the two dams for the period above named. 



In Tables I. and II. are to be found tabulations of the ex- 

 tremes of low and high water, the range of movement, and the 

 total of the + and - movements for each month in the periods 

 covered by the records at the two dams. The appended table 

 also gives some data pertaining to the major fluctuations at 

 Copperas Creek. The rainfall statistics refer to the state as a 

 whole and are taken from Leverett ('96). 



From the data presented in the hydrographs and these 

 tabulations the variations and the average condition of the 

 Illinois River may be determined, and some estimate made of 

 the normal regimen of the stream. In general terms this is as 

 follows: There is in each year a period of high water — that is, 



