IOWA ACADEMY OF SCIENCE 
157 
-In other words, channel conditions cannot be maintained, except the flow 
of water can be placed under control and lastly, the expensive program 
of large channel construction would have been rendered very largely un- 
necessary, so that by the correction of the major crooks of the native 
channel, it would have been rendered capable of doing all the work re- 
quired. The additional advantages of such a program of reclamation 
and river control, need not be discussed. The possibilities of water- 
power, so valuable now as a means of extension of rapid transit facili- 
ties, are evident. The possibility of irrigation of the flat lands of our 
river valleys by constructing irrigation laterals on the two or three river 
terraces are so obvious that our reclamation service engineer need not 
mention them to us. . Who among you is not willing to admit for a mo- 
ment that Iowa has not seen the time when irrigation would have bene- 
fitted much of her acreage^ Who among you is willing to admit that 
Iowa soil is not capable of producing as valuable and profitable crops as 
any lands? Those of you who are familiar with the sub-soils of these 
river fiats, are aware that they will readily lend themselves to irrigation ; 
that they are seldom underlaid with impervious sub-soils and, in nearly 
every case, have gravels which render these soils peculiarly subject to 
crop loss in times of drouth, this same condition being most favorable 
for absorbing and using all waters applied by irrigation methods. Lands 
underlain by . impervious sub-soils frequently require artificial under 
drainage in order for irrigation methods to work most successfully.’ 
The tile drainage of these lands is being carried on at a rate per acre 
which will total when all lands needing it are well drained, about $300,- 
000,000. The effect which this, tile drainage produces is to lower the 
ground water level to an average of about three feet or in wetter times 
24 to 30 inches below the surface. This creates a porous soil cap which 
is capable of absorbing about 15 to 20 per cent of its bulk of water. This 
means that 30 inches of soil that is drained will absorb 4% inches of rain- 
fall in about 48 hours without erosive run-off or leaving standing water 
in the depressions. 
What this means in the solution of the problems given before can 
merely be suggested. But certain facts we know. There can be no bet- 
ter reservoir than a soil capable of absorbing this rainfall. We know 
by guaging of ground water level in drained lands that a rainfall is ab- 
sorbed quickly and fed slowly off to the river through a period of many 
days and often weeks before the original low ground water level is 
again reached. 
The remarkably heavy snowfall reported variously at from 64 to 84 
inches in the Wisconsin Drift area, winter of 1909-1910, thawed in about 
