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 Pl. 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; 2.5 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 0n 3 days, at 2.2 
on 2 days, at 2.1 on 3 days, at 2.0 on 32 days, at 1.9 on 25 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 Pl. 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. 
