MICHIGAN ACADEMY OF SCIENCE 
99 
SYMPOSIUM ON WATER SUPPLIES IN MICHIGAN. 
GEOLOGICAL CONDITIONS OF MUNICIPAL AND INSTITU¬ 
TIONAL WATER SUPPLIES IN MICHIGAN.* 
FRANK LEVERETT. 
SOURCES OF SUPPLY. 
The details concerning the sources and geological conditions of the 
public water supplies of Michigan are found in the table presented be¬ 
low. From this table it appears that the Great Lakes and their con¬ 
necting streams supply thirty-seven cities and villages with an aggre¬ 
gate population of about 500,000; the inland lakes seventeen towns with 
a population of 65,000; the inland streams forty towns with a popula¬ 
tion of about 200,000, while impounded water is used in seven towns, 
with a population of 11,200. Springs are drawn upon wholly or in 
part by eighteen villages and three institutions with a population of 
about 30,000. Infiltration wells are drawn upon by five towns with a 
population of 39,000. Underground supplies are from the following 
sources: (a) Shallow drift wells, either excavated or driven, supplied 
from the surface part of the ground water, used in twenty-seven cities 
and villages, including Muskegon and South Haven which have pipes 
under the lake bed and are included also in the thirty-seven towns sup¬ 
plied from the Great Lakes, with a population of over 80,000; (b) wells 
carried deep into water bearing stratum but without passing through 
an impervious bed, in use by eighteen towns with a population of about 
45,000; (c) wells from gravel or sand under clay in use by fifty-one 
towns and institutions with a population of 100,000; (d) shallow rock 
wells, less than 100 feet in depth, in use in four towns with a popula¬ 
tion of 5,765; (e) deep rock wells, 100 to 600 feet in depth, in use in 
twenty-five villages and five institutions with a population of about 
100,000. Of this last class twenty towns with a population of 88,150 
and the five institutions with 3,800 draw water from standstone, leav¬ 
ing only four supplied from limestone. 
''' v/' J 
CHARACTERISTICS OF SURFACE WATER. 
Hardness. The waters of the Great Lakes and their connecting 
streams (St. Marys, St. Clair and Detroit Rivers) are found to contain 
a smaller amount of mineral matter and to be softer than the average 
waters of the inland lakes and streams, there being only one-third to 
two-thirds as much calcium and magnesium carbonate in the waters of 
the Great Lakes as in the inland rivers. This results naturally from 
the fact that a large part of the supply to the Great Lakes is by direct- 
rainfall, the area of the lakes being nearly half that of their watersheds, 
* Published by permission of Director of U. S. Geological Survey. 
