The Wenatchee daily world. [volume] (Wenatchee, Wash.) 1905-1971, 1907-08-14
The waters Of the Great Lakes.


The investigation of the quality o.
! the waters Of the great LIKES. begun ,,y
the United States geolcgfcal sarvey
about nine months ago. has reached !,
poiut where interesting results atr
available.
The object of the work was to deter
mine the quality of the waters carried
by the great lakes aud the changes
that take place in their mineral con
tents between the head of Lake SUI
perior and st. Lawrence river. For
this purpose samples of water were
collected from each OF the lakes ut reg
ular intervals and shipped to the iabo-
ratoly of the survey ut Washington for
mineral analysis Says the government
report:
The analyses show that the waters bold
III solution varying quantities of calcium
and magnesium compounds, which. from
their tendency ia form scale or incrusta-
tons boilers. are called incrustants.
Named in the order OF the total content
of iNcrustants, beginning with tho lowest.
The lakes rank as follows: Superior. HUI
ron, Michigan. Ontario ana Eric. The Wa
lers of Lake Michigan and Lake H-lr0n
are, nearly identical in quality. aDd the
. same may be said Of those of Lake Orta-
rio and Erie. Lake Superior. howevcr.
carries just about half the amount OF in
crustants borne b. tie other lakes.
The reason for this variations is found in
the geologic formations that surround the
lakes. The streams flowing into Lake su-
perior drain areas composed chiefly OF
cry stalline rocks. which yield scant gIian-
titles of mineral matter to waters fiawi-l.,
through them: the streams entering Lake,
Michigan and Huron. on the other hand.
traverse regions made up largely of soll-
BILE sedinentary roc,.S-llmesiones. sand
stones and clays- which yield to tie wa-
tiers comparatively large amounts OF the
calcium and magnesium compounds. The
difference In mineral content between
Lake Huron and Lake Michigan results
from the dilution Of the water of Lake
Huron by the softer water Of Lake Supc-
rior. Lake Erie Is highest in incrustants
because it receives not only the waters
from Lakes Michigan :nd Huron, but the
drainage from immense areas OF sedinien-
tary rocks in Indiana and Ohio and In the
province of Ontario The waters of Lake
Ontario are softer than those Of Lake
Erie because they have been diluted by
drainage from areas of crystalline rocks
In New York and the Canadian province.
The water Of all OF the lakes is modified
greatly by the large amount of rain and
snow directly added TO their surfaces.
serving to measurably lower the proper
ton of mineral matter. The quality of
the water In each lake varies but little
from month to month; the variation is.
however measurable, and In winter the
mineral content is higher.
The lake water is, as a rule. very
clear, containing practically no sus
pended matter except in times OF
storms. when the sand and deposited
organic matter near the shore are stir
rel UP by wave action. 1t has been
computed that more than o9,0O00OO
tons of mineral matter. chiefly calcium
compounds. held invisibly in solution,
are annually carried from Lake Erie
to Lake Ontario over Niagara falls.
But Notwithstanding this enormous
amount Of dissolved material in their
waters the investigation proves con
clusively that as long as the great
lakes remain unpolluted by sewage
they will afford the region surrounding
them the best available water supply
for municipal and industrial uses.