Great Falls tribune. [volume] (Great Falls, Mont.) 1921-current, 1922-04-30
It a cost within the reach of the dis

at a cost within the reach of the dis
trict.
To get an idea of the proposed sig,
of the Two Medicine dam. it may b,
stated that at it's highest point, it vii
be 149 feet high with a top width o
20 feet and q bottom width of 16j feet
1t will require 3,352.367 cubic yards t.
make the embankment and take tive
working seasons in building with tn.
largest size suction dredae made. L
will have a storage capacity of 1S2,5O
acre feet. If it were used as a water
supply for Great Falls and water wer.
used at the ate of 10000 gallon.
a day. it would take nineteen years t.
empty it.
Besides the two reservoirs men
toned. a diversion dam has been de-
signed on the Cut Bank river of the
same geenral design.
As these dams must never be over
topped. spillways have been designd
of sufficient capacity to pass a flood
twice as large as the peak of any flood
recorded in the past.
Two Secondary Reservoirs
Besides the reservoirs mentioned.
two more reservoirs have been de-
signed. These reservoirs. known as
the Willow Creek and Lost Lake reser-
voirs, are located near the land to be
irrigated and are known as secondary
reservoirs. The total storage capacity
planned for the -four reservoirs is 43O,-
SO acre feet.
The waters of Two Medicine and
Badger are to be carried in a canal by
gravity and dumped Into Cut Bank
back of the diversion dam: from here
another canal will conduct the COM
bined waters to the land to be irri-
gated.
In the ordinary projects. it is nee
essary to construct the main canals of
sufficient capacity to meet the peak
demand for water. As the peak de-
mand for July is from 30 to so per
cent of the entire quantity used, it will
be seen that much capacity must be
provided which is only used one month
in the year. On the Too2e county prof.
ect. through the building of the see
ondary storage reservoirs, it Is posi-
bic to operate the main canals at 100
per cent of their capacity from April
| to October 1. or six months. Dur
ing the time of little Or no demand. the
water not needed for irrigation is used
to fill the secondary reservoirs. Dur
ing priods of large or peak demands.
water is supplied not only from the
main canal, but also from the water
heretofore stored in the secondary
reservoirs. This tends to make a very
flexible system, a system where the
main canals can be used much more
efficiently and where the water lost
through regulation will be small.
In the olden days (the "Days of real
all that was necessary when an
irrigation project was to be started
was to I'll a line of lovelus about
the main canal was to be built
and assume that all the land lying at
a lower elevation was irrigable. I'm
or fortunately, it isn't pos
sible today to do business that way. An
irrigation project today must be placed
on a firm business basis. Every item
that will effect the success of the prof.
ect must be analysed to its last detail,
nothing must be left to the imagination.
the case of the Toole county irri-
cation district, this examination and
study took two and one-half years Of
time and cost over %one-fourth Of a mil |
lion dollars. A topographic survey was
covering 100000 acres in suf-
Ficient detail so that maps could be
prepared showing mi foot differences
n elevation owe this entire area. All
the land was classified as to being
for irrigation. Tracts from
acre to thousands of acres
we're marked for elimination because
IF soil conditions or because the sur
ACE was too rough, steep or rocky.
After the Topographic maps were