MICHIGAN ACADEMY OF SCIENCE. 
101 
The inland lakes are in some cases shallow and rendered turbid by 
storms, but a large number of them occupy deep basins with only 
a narrow fringe of shallow water so that it is an easy matter to extend 
the pipes into water that is always clear. To many lakes the trib¬ 
utary streams are of little consequence and there are very few in which 
a marked turbidity is caused by the inflow from streams. In marl 
lakes however, there is in some cases constant turbidity because of the 
action of waves on the marly shores. 
Lake currents in reference to contamination. Lake currents become 
of vital interest in connection with several of the public water supplies 
of Michigan cities. One of the most striking instances is that of Mar¬ 
quette. The waterworks supply is taken from a harbor north of Light 
House Point from an intake pipe which extends only 850 feet into 
the lake and terminates in 26 feet of water. The sewage is all carried 
into a harbor south of Light House Point. The shortness of this 
intake pipe suggested the advisability of taking water from farther out, 
but fortunately the city took the precaution to test the water through¬ 
ly before making the extension. A small test pipe was carried out to 
a distance of 3200 feet and samples have been taken from it monthly 
for the past year and, together with samples from the present intake 
pipe, were sent to the Hygienic Laboratory of the University for ex-, 
animation. The superintendent of the waterworks informed the writer 
last October that the analyses of water from the long pipe showed 
greater contamination than that of water from , the short pipe. The 
long pipe appears, therefore, to be in the path of a current leading out 
from the sewer laden harbor while the short pipe is out of the path of 
that current. While therefore, in general, the greater extension of 
pipe tends to secure a better water, in this case it may secure a poorer 
water. 
On Little Bay de Noe are two neighboring cities, Gladstone and 
Escanaba, one of which has felt no serious results from the use of the 
water from the bay while, the other has for several years been ravaged 
by epidemics of typhoid fever. Gladstone, the favored city, stands 
nearer the head of the bay and opposite a very narrow part. Streams 
entering the head of the bay cause a preceptible current past this 
narrow part so that the sewage is seldom or never carried to the in¬ 
take pipe. Escanaba is not so fortunately situated and the currents 
appear to mingle the sewage with the water taken for the city con¬ 
sumption at such frequent intervals as to greatly pollute the supply. 
Plans are now pending for the installation of a filtration plant to 
purify the water, but it is unfortunate that the city has turned its 
sewage and allowed the sewage from a hospital to be turned into its 
source of water supply, when it might at a slight additional expense 
have turned the sewage into a stream back of the city which would 
have carried it beyond the part of the bay from which the city supply 
is taken. However, contamination may occur in lake ports, such as 
Escanaba, from diseased persons on vessels standing in the harbor as 
was the case at Sault Ste Marie, so that a filtration plant should be 
installed in every lake port which draws its supply from a harbor. 
Inasmuch as the sanitary conditions of the water supplies will be 
treated by another it is unnecessary to go farther into the matter at 
this point. 
