226 National Geographic Magazine. 
reality owing to the great percentage of loss by seepage and 
evaporation, little or none of the water entering at the headgates 
will ever reach the irrigable lands. © 
Such illy advised projects are to be even more deplored than 
the smaller operations before spoken of, since the certain ulti- 
mate failure of this class of enterprise will result in discouraging 
capitalists from investing in even well-planned irrigation pro- 
jects, and will retard the construction of valuable and necessary 
works. 
PossiBLE IRRIGATION ENTERPRISES. 
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. 8. Geological Survey in speak- 
ing 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 pro- 
ductive regions. The same statements apply to the canals pro- 
jected, though of course detailed surveys may prove the imprac- 
ticability 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 suc- 
cesses. 
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, 
