136 
IOWA ACADEMY OP SCIENCE 
large percentage of plowed land, the fine soil and clays, their waters are very 
turbid most of the year. In short, such streams as we who cast the fly find 
in Michigan and Colorado, with their strong currents of pure, clear water, 
derived from springs and forest covered sand layers, or from melting snow 
above the habitations of men, are unknown in Iowa. According to present 
sanitary standards there is no river in Iowa or on its border whose natural 
waters may be used the year through as the source of municipal supplies. The 
situation is likely to become worse rather than better as the population be- 
comes more dense and the industrial interests expand and multiply. Unless 
some practicable plan of filtration adapted to the smaller places is devised 
it seems probable that rivers as the source of such supplies will continue to 
be of secondary importance. 
Iowa is a state having few lakes of consequence. The only ones of im- 
portance form a group near the northern border of the state and well to the 
west. They are far removed from centers of population, they are fed by small 
streams, are shallow and they cannot be considered suitable the year around 
for town supplies. The same physical features that cause insuflB.cient and poor 
river water also make large reservoirs or artificial lakes of good water prac- 
tically unobtainable. 
It is an interesting and important fact that the most of the conditions that 
contribute to make the rivers of smaller importance are the ones that increase 
the ground water resources and its easy availability. The level surface, the 
porous soil and drift, the large percentage of cultivated land increase the 
percentage of water absorbed. The deep soil and subsoil, the sand and gravel 
of the drift afford it storage. This filtered and stored water is in most regions 
easily reached by the bored well or the sand point. In very many areas the 
sand and gravel layers lie in basins or troughs and in such regions flowing 
wells are secured. In some regions such water-bearing layers are struck high 
in the drift, but a very large number of wells go to the rock and derive their 
water from gravel layers just above it. 
The level nature of the land may also account for the fact that for the most 
part Iowa rivers and streams have low velocities of flow and meander through 
wide level valleys, instead of flowing with high velocity between ranges of hills 
as in more rugged countries. In such valley-plains of rivers, water supplies 
can be secured from the so-called “under-flow.” In the southwestern part of 
the state where there are many such streams this source seems to be the best 
and the most generally resorted to for town water systems. Good examples are 
Atlantic, Red Oak, Elliott and Griswold on the Nishabotany. Such waters have 
the advantage that they contain about the same amount or very little more 
mineral matter than the waters of the rivers themselves. 
There remains to be mentioned the unparalleled source of well water in the 
northeastern part of the state, — the sand-stone layers of the Cambrian and 
Ordovinchian systems, known as the St. Peter, New Richmond, Jordan and 
Dresbach. This magniflcent source is too well known to require further men- 
tion. It may be of interest to note, however, that in at fewest flve of the 
most favorably located counties this source is untouched, and in several others 
one flnds only one or two wells to each county. 
Such are the well water resources of the state. To what extent are they 
being used or to what extent are the people dependent upon them? That well 
waters have up to this time held the most important place appears strikingly 
