The Cairo bulletin. (Cairo, Ill.) 1???-1928, 1910-01-31

traverse the intervening river, After
teh discharge has been commenced
at Lake Wmnibigoshish. its effect is
not especially felt at Lake Pokegama.
the distributing reservoir. sixty-three
miles further down stream until after
an interval of twenty-one days at low
water, nor at ST. Paul, 3Gl miles be-
low Pokegama. until after a further
interval of ten days. In order to use
this reservoir system for the benefit
of the Improvement of the river below
ST. Louis, il would be necessary the
discharge of the reservoirs at least
two months before it was needed at
ST. Louis, and a still greater interval
would be necessary for the benefit OF
Cairo. Experience does not justify
such long forecasts, and the service
of the reservoirs would necessarily
, have 10 be based on general annual
averages, an unreliable and unsaus-
factory basis. There have been oc-
casions in the past when unexpected
| floods in the summer time woulil
lhave been aggravated by any large
additions from upper reservoirs. In
order that reservoirs may give rell-
able service, they should be so 10
Gated as TO diminish time of water
flow TO a minimum. In the case un-
der consideration this would neecssi-
tate the location of the reservoirs in
the lower valleys Of the tributaries
where the land is of great value, and
such location would add enormously
to the cost of the reservoir system
even if it were practicable.
While this method of improve
upper Mississippi near St Paul t
the limited extent above described
a further extension OF its application
Ito a river of the dimensions Of the
Mississippi below ST. Louis is attend
ed with serious difficulties and must
necessarily give results fuch less
beneficial
Theoretically water supply s
available above St Louis sufficient
to increase largely the low water dis
lcharge of the Mississippi river at and
below st. Louis. The maximum
reservoir facilities Of the river, in
Guiding 10000 cubic feet per second
that may come through the Chicago
drainage canal and Illinois river, as
recommended by the lnternationa
Waterways Commission, amount tt
about $500 cubic feet per secont
for ninety days, equal to about $40,
100000 900 cubic feet total storage.
Moreover. dam could be con
structed across the mouth of the Hi
nois river, with a height Of only ,,
feet above low water 70 produce ;
! reservoir over 227 miles in length il
a valley in which over 100000 acre!
have been subject to overflow in thu
. past during ertreme floods.
The maximum of $40 billion eubi'
fleet total storage which might be OBJ
ltained by reservoirs in the MISSISSIPPI
river basin from the Illinois river up
l. ward could not maintain Throughout
d the year more than eight feet avail
able depth between st. Louis AM
ICairo, the increased discharge from
4 the reservoirs tending to create
{ wider channel rather than deepe
h one, and being useful therefore, onl
as an auxiliary to other methods o
r Improvement, To hold the wate
y stage at St. Louis at % feet, tn,
Z stage corresponding to a controlling
depth OF fourteen feet between 81
+ Louis and Cairo. would require owe
$ 5000 billion cubic feet annual stoi
I" age, or about ten times what has We
been found possible"