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RIVERS AND STREAMS
The flow of Michigan’s river and streams is remarkably uniform in comparison with
streams in many parts of the country. This uniformity of flow comes about in part from the
shape of its river basins and in part from the seasonal pattern of its precipitation.
Also, many of the streams in the northern parts of the state flow within sandy watersheds,
where they get slow, steady contributions of groundwater, and not much water via storm
runoff–making for steady, cool flow within and for good trout fishing! None of
Michigan’s rivers are long and the most important ones, draining only a narrow band
in their lower reaches, mushroom out in their upper ranges to storage areas of marshland
with innumerable lakes. Thus, floods are infrequent and seldom serious so that artificial
regulation of stream flow is required only in scattered instances.
Michigan’s geological base is also a favorable circumstance for
rivers. Underlying the state is a bowl shaped depression of rock strata known as the Michigan Basin– the rims of this basin are as far east as
Buffalo and as far west as Wisconsin. The basin contains the whole of the Great Lakes and
in their center lies a mound of sedimentary rocks and glacial deposits. The glacial
deposit consists of many layers of sand, clay, gravel and boulders, admirably suited to
hold vast quantities of water at many levels. The geological detail of these underground
reservoirs and streams is still largely unknown and their sustained yield a matter of
speculation but the limit of their yield has certainly not been reached. Large cities such
as Pontiac, Jackson, and Ypsilanti are supplied entirely by wells without serious lowering
of the water table.
Before settlement of their basins, streams typically ran clear
year-round because natural vegetation prevented soil loss. Clearing of the original forest
for agriculture and logging has resulted in both more erosion and runoff into the streams
and lakes. This accelerated runoff aggravates flooding problems.
Parts of the text on this page have been modified from L.M. Sommers' book
entitled, "Michigan: A Geography", and from the
NOAA Publication, "The Great Lakes An Environmental Atlas and
Resource Book" (1995).
This material has been compiled for educational use only, and
may not be reproduced without permission. One copy may be printed for personal
use. Please contact Randall Schaetzl (soils@msu.edu)
for more information or permissions.
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