Burlington weekly free press. [volume] (Burlington, Vt.) 1866-1928, 1908-09-10
THE WATERS OF
THE GREAT LAKES
Reports in Preparation By the u. 8.
Geological Survey.

0rVIVHiVuI survey.
More than four million people. living
| in hundred cities. obtain water for
| domestic and Industrial uses from the
great inland seas on the northern
| boundary OF the United States and boil
| err water for the enormous land and
water traffic that Joins these cities to
| one another and to the rest of the world
| Is derived from the Same source The
| chemical composition of these waters is
| therefore n matter OF great interest to
both sanitarians and chemical engineers,
| and n study OF that composition is also
| valuable because the comparative euu-
| able condition OF the lake waters allows
| them to serve as standard for compar-
| ison with other waters In the northern
| region.
About two years ago the United States
| geological survey began n study OF the
| waters of the Great Lakes In connection
| with n rather extensive investigation of
the economic value of surface waters In
| the United States. For a year n l-gal-
| Ion sample was collected each month
! from each lake at Il point where the
water would probably represent the nor
NAL quality of the discharge. Samples
| OF Lake Superior water were taken from
| St. Mary's River Just above the locks at
| Saulte Ste. Marie. Mich the Lake Michi-
| gan samples were collected from n ferry
| boat in the Straits of Mackinac: St.
| Clair River was sampled IN midstream
| at Port Huron Mich. Lake Erie was
sampled at the Buffalo On. " water
| works intake; and St Lawrence River
| was sampled at Ogdensburg. y. y.
| since no important streams enter be-
| tween that city and Lake Ontario. The
| waters were shipped in special contain
ers to the water-testinR laboratory Of
| the survey Mt Washington, y. c.. and
were analysed from ono to three months
after date Of collection. Suspended mat
ter was removed before the samples
were evaporated, and standard methods
Of water analysis were followed when
practicable.
Mr. NJ. p. Dole, under whose direction
| the analysis were made. states that the
| most noticeable feature In n cusory ex-
| animation Of the analytical data IS the
slight variation in the concentration OF
| the waters from month TO month. the
total variation ms shown by the dissol-
we'd solids figures, being only ls parts
ordinary size may vary 30 to 900 per cent
| and even large rivers. like the Mlssis-
sippi. may change 80 per cent in their
mineral content during the year. this
annual huctuation Of IS per cent is very
| small. The average monthly fuctuation
In the discharge Of the Great Lakes is
| considerably more than Is per cent,
ranging from 40 por cent IN st. Mary's
| nj - tv, n m
river at the foot " Lake Ontario. The
chemical composition Of the water does
not, therefore. bear fixed relation to
| the quantity of water discharged. Mr..
Dole gives as the probable reasons for
this comparative stead!ness in concen-
tration the absence OF large tributaries
| and the low ratio, between the areas of
the drainage basins md the lake sur
faces
Though the lake waters do not
| change greatly from month to month.
they differ great deal from one an
other In concentration. Like Superior Is
least strongly minerallzed. Lake Michigan
Is twice as high in total solids, and Lake
Huron Is but little less minerallzed than
Lake Michigan. Lakes Erie and Ontario
are practically alike IN mineral content
holding about zig times as much solids
In solution az Lake Superior Reason
for the striking difference in the lake
waters 8 found In the character of the
geologic formations in the drainage has
ms tributary TO them. The crystalline
and igneous rocks-granite. schist
gneiss and basalt-that predominant all
around Lake Superior are not easily
soluble and hence tho lake receives few
affluents bearing large quantities of dis
solved matter Lake Michigan and Lake
Huron on the other hand. receive drain
age from iimestones and sandstones OF
the sedimentary series and contain much
greater proportions Of mineral matter
D,ution by the softer water Of Lake
Superior probably accounts for the fact
that Lake Huron water Is less mineral
lied than that Of Lake Michigan. It Is
probable that forestation. sedimentation
and re ~tion Of rainfall 10 r-n-off also
affect the relative composition Of the
lake waters.
Compa rison OF the analyses of the lake
waters with those Of tributaries to the
system shows. according TO Mr.. Dole
that the lakes are almost invaria bl,
softer than their affuents. The reason
for this difference Is apparent: As the
lake surfaces are large In proportion tc
their corresponding land drninages, a
great part OF the rain falls directly into
the lake waters and dtlutes them. On
the other hand. rain falling upon the
land becomes more or less impregnated
with mineral salts before It reaches the
lakes In the normal run-off. This fact
has an important relation TO the indus
trial consumption OF the waters. and
shows the Importance Of locating In
takes outside ~ the influence OF tri-
butary streams.
A study OF all tho data at hand leads
to the conclusion that tho lake waters
may be specially recommended for IN
dustral and domestic uses wherever
they can be economically obtained. They
are low in mineral content and normally
free from turbdity. and the nature OF
the dissolved constituents Ia such that
they can be used for boilers and for
most other industrial purposes without
publication.
Reports on the quality OF surface
waters In various parts of the United
States are now In preparation.