During the past season the author made an extensive though hurried
reconnoisance of Montana, in the progress of which he rode on horseback
2,200 miles and traveled 3,700 miles by rail, examining with some
degree of detail all of the central counties and making a few hasty
trips into Choteau, Dawson and Custer Counties. In the course of this
reconnoisance the sites for sixty storage reservoirs, having a combined
storage capacity of about 3,250,000 acre feet were carefully examined,
and lines of ten great irrigating canals approximately decided on. It
may be well to state here that an acre-foot of water is a very
convenient unit of measure adopted by the U. S. Geological Survey in
speaking of the contents of large reservoirs, and refers to a body of
water one acre in superficial area and one foot in depth.
In every case these proposed reservoirs are so situated, that their
storage water will be convenient to large bodies of irrigable land,
which, without some such provision for water supply must forever remain
uncultivated, but which with irrigation from these reservoirs will
ultimately become thickly inhabited and very productive regions. The
same statements apply to the canals projected, though of course
detailed surveys may prove the impracticability of some of these works
as financial investments.
Mention will be made of a few of the more important of these projects;
those which appear most likely to prove financial successes.
North of the Yellowstone and between it and the Musselshell and
Missouri Rivers is an immense high bench land, traversed by a few long
couleés, dry excepting in the times of melting snow or heavy spring
storms, and then raging torrents for a period of a few days or hours.
This bench land between the couleés is flat topped and has a regular
and gentle slope to the eastward, falling about six feet per mile, a
little more rapidly north of Big Timber, and decreasing in grade to the
eastward. The general elevation of this bench above the Yellowstone
River varies from 600 feet north of Stillwater, to 300 feet north of
Miles City, and includes about 11,000,000 acres, of which at least
5,225,000 acres are of the best quality for agricultural purposes and
readily accessible by the great canal. In all this vast area there is
not even sufficient water for the few horses and cattle which range on
it, and they are compelled to congregate near the occasional pools and
springs scattered at long intervals over it.
From numerous examinations made hastily with aneroid and hand-level, it
seems likely that a great canal can be taken from the Yellowstone,
somewhere in the neighborhood of Livingston, or lower down the river,
and led upon the summit of the bench with a diversion line not over 100
miles in length. Taken out at Livingston the canal would encounter no
difficult construction, and would chiefly consist in earth excavation
with very little rock work. It would require a few fills and flumes in
crossing the larger side streams, such as the Little and Big Timber,
Otter and Sweet Grass Creeks. It would reach the summit somewhere north
of Merrill at an altitude of about 4,400 feet and thence could be
conducted with an easy alignment eastward, with occasional falls to
loose grade.
The water flowing in the Yellowstone River at Livingstone during the
irrigating season this year averaged 2,300 cubic feet per second,
which, with an allowance of thirty per cent. for loss by seepage and
evaporation in the canal, would leave about 1,600 second feet at the
point of utilization or sufficient to irrigate 160,000 acres.
The average normal discharge from Yellowstone Lake is 700 second feet,
and a dam about 300 feet long and less than ten feet high, constructed
below the outlet of the lake, would store the outflow from October to
May, inclusive, eight months, a total including flood discharges of at
least 600,000 acre feet, an amount which, allowing for loss by
evaporation in the lake, and by seepage and evaporation in the canal,
would irrigate 425,000 acres, in addition to the 160,000 acres
previously mentioned. Besides this volume probably half as much more
can be readily stored on the Lamar and Gardner Rivers, and the other
branches of the Yellowstone which join it above Livingston, bringing
the total area of reclaimed land to nearly 1,000,000 acres.
There are many similar and even better opportunities for irrigation
development, such as the construction of a canal from the West Gallatin
River near Bozeman. This canal would require no expensive diversion
line, as its waters would become immediately available at the
headworks, and by appropriating the 500 second feet of water flowing in
the river, would reclaim at a minimum cost 50,000 acres, or twice the
amount of land now cultivated there. Storage on the Upper Gallatin
River would greatly increase the amount of reclaimed land.
Storage reservoirs can be easily constructed on the headwaters of the
Beaver Head River, whereby at least 150,000 acres could be added to the
25,000 acres now under cultivation in the Beaver Head Valley near
Dillon.
A canal requiring no diversion line can be taken out on the east side
of the Missouri River near Toston, which will irrigate all of the good
land in the Missouri Valley, at least 100,000 acres. This canal would
require some fills and aqueducts in crossing the various side steams
such as Deep and Duck Creeks, and Confederate Gulch.
Detailed surveys have been made during the past summer on the Sun River
which indicate that storage will add some 250,000 acre feet to the
amount of water in that stream now available for irrigation. There are
at least 600,000 acres of good agricultural land between the Dearborn,
Sun, and Teton Rivers, which must forever remain barren of cultivated
products unless provided with water by means of storage on these
streams, and the surveys above alluded to indicate that by this means
160,000 acres of this land can be reclaimed by the Sun River alone.
Mention might be made to many more similar projects, such as the
construction of a simple canal from the Missouri River to irrigate
Chestnut Valley, south of Great Falls, whereby 120,000 acres would be
reclaimed; or one from the Upper Madison River whereby 230,000 acres of
the Madison Valley might receive water, but the foregoing will suffice
to show the possibilities of irrigation development in Montana.
It would be doing the resources of a great and vast area of Montana
injustice if reference were not made to the Milk River country, the
great Indian reservation of 17,680,000 acres in the northern part of
the State which has recently been open to settlement. This region has
not been examined by the author, but from conversations with a number
of its well-informed inhabitants it appear that the soil is very
fertile, and that during average moist years excellent crops can be
raised there without irrigation. This last statement, however, should
not be too readily accepted. It is probable that some storage water may
be retained in the hills along the British line, though its development
will doubtless involve international questions.