118 



From Peoria to Pekin and again from Copperas Creek 

 dam to Havana there are narrower reaches whose average 

 widths fall to 604 and 603 feet respectively. The depth of the 

 river at natural low water varies from .8 of a foot upon some 

 of the bars to more than 14 feet in the deepest channels. The 

 average depth from Copperas Creek to Havana is about 9 feet 

 and the average cross-section 2,801 square feet. Between 

 Havana and the LaGrange dam the river becomes more shoal 

 again, as is usual below the mouths of the larger tributaries. 



According to figures given by Cooley the dam at LaGrange 

 raises the level of the river at Havana 2.4 feet. During 1894, 

 a low-water year, no records of the river-gage were kept at 

 Havana, but at the time of the exceptionally low water of 



1895 the gage-reading (see PI. VIII.) repeatedly fell below the 

 level assigned by the engineers to this point in the pool of the 

 dam. From January 12 to February 22 the gage ranged from 

 2.4 to 2.2, standing the greater part of the time at the latter 

 reading. Again, from June 10 to July 16 it stood below 2.4, 

 reaching the minimum reading 1.7 on June 23. On August 10 

 and from the 14th to the 23d it stood below 2.4, and so also on 

 September 3 and from October 4 till November 7. During the 

 year the gage read less than 2.4 feet on 111 days ; 2.3 on 41 

 days, 2.2 on 46, 2.1 on 17, and 2.0 to 1.7 on 7 days. During 



1896 the gage fell to 2.4 on but a single day, July 19. In 1897 

 the gage read 2.4, or below, on 84 days — from August 9 till 

 October 31. It stood at 2.4 on 3 days, at 2.3 on 3 days, at 2.2 

 on 2 days, at 2.1 on 3 days, at 2.0 on 32 days, at 1.9 on 23 days, 

 at 1.6 on 11 days, and at 1.7 on 7 days. In 1898 the lowest 

 point reached was 2.5 The dam at LaGrange is estimated to 

 raise the water 2 feet on the lower gage at Copperas Creek 

 dam, but during 1897 the readings at this place during the pe- 

 riod of lowest water very nearly coincided with those at 

 Havana (see PI. VII. and X.). The coincidence of the readings 

 would indicate that the gages at the two places have not been 

 correlated, since under the conditions the gage at Havana 

 should read somewhat higher than that of Copperas Creek. 



