IOWA ACADEMY OP SCIENCE 
135 
SOME FEATURES OF IOWA GROUND WATERS, II. 
BY W. S. HENDRIXSON. 
About two years ago the writer read before this body a paper, under the 
above title, giving a general statement of his work on the quality of Iowa, well 
waters. The accumulating experience of the past two years seems to justify 
at this time a statement of some additional facts that seem important and 
which may be of interest to the Iowa Academy of Science. 
The analytical work on which the author has been engaged is now practi- 
cally discontinued, not completed since the field seems almost without limit, 
and at present the results are being put in form for publication. During 
the course of the work there have been accumulated about four hundred 
analyses of the waters of wells of importance. These wells are fairly dis- 
tributed throughout the state, and there are representatives in almost every 
county in the state. A total of about one thousand analysis and nearly as 
many descriptions of wells have been at hand to give good opportunity for 
generalizations on the subject under discussion. It is proposed in this com- 
munication to confine attention to three topics, the availability of ground 
water in this state, the present and probable future development of this re- 
source, and the softening of hard water for industrial uses. 
Certain physical features of the surface of the state of Iowa which contribute 
to decrease the importance of its surface waters as compared with other states 
are almost too obvious to require statement. 
This is a state of comparatively level surface; that is, the differences of 
elevations above sea-level are small. Taken in detail its surface is gently 
undulating. There are no mountains, and scarcely anything worthy of the 
name hills. Ninety-five per cent of the surface is tillable and nearly the 
whole of it is under cultivation. There is thus very little wild land or forest 
area as compared with eastern states, to serve as collecting ground for lakes 
and rivers of good water. The soil is very deep and generally very fine and 
porous. Under it are the comparatively porous loess and .the sand and gravel 
of the drift. . The drift covers nearly the whole state -and is very deep, over 
most of its surface. Though the state has an annual rainfall of nearly thirty- 
five inches, these conditions contribute to make the run-off small and the 
amount of water taken up by the ground very large. Owing to the deep drift 
covering the rock strata, the scarcity of outcrops and the generally unbroken 
surface of the land, perennial springs that might feed the streams during dry 
weather are comparatively rare. Without this source of supply, without forest 
areas to hold the water back, and with the porous soil to take up nearly the 
whole of the rainfall of the drier months it follows that many of the small 
interior rivers of the state contract to insignificance during the dry periods, 
usually of the summer and early fall. At all times and specially during the 
dry seasons their waters are subject to pollution by the surface drainage, 
sewerage of towns and commercial concerns along their courses. Owing to the 
