PLANS FOR EXTENDED IRRIGATION. 
313 
per second-foot; in Valencia, above 200 acres per second-foot, and in Elche, where 
water is very scarce, a second-foot is made to do duty for 1,000 acres. Of course such 
crops as rice require much more water, giving a very low duty. 
Hon. G. P. Marsh, in his well-known work, "Man and Nature," after discussing this 
question thoroughly, comes to the conclusion that 200 acres to the second-foot is a safe 
allowance. The United States commissioners, referred to above, who made an exam- 
ination of the great valley of California, came to a similar conclusion. Mr. W. H. 
Hall, State engineer of California, concludes by saying that this duty, at least, can be 
reached. Indeed, it seems to be a generally accepted conclusion, that, with the aver- 
age of crops and soils, and without considering the rainfall, the duty should reach 200 
acres per second-foot. Iu Utah, the practice is, as was above stated, but 80 to 100 
acres. Iu Colorado it is much less, probably 40 or 50 acres. 
To arrive at any definite knowledge concerning the amount of arable land in the. 
West, it will be necessary in the cases of nearly all the streams to institute a system 
of gaugings, to be made at intervals not greater than once a Aveek, to extend through- 
out the year at least. The simplest way to carry this out would be to have a section 
made of the river channel at the point selected for the measurements, the section to 
extend to the marks of the highest floods on the banks. A gauge- rod, suitably placed, 
and read at the designated times, with measurements of current velocity at the periods 
of high, medium, and low water, would give data for the computation of the capacity 
of the stream. Until this is done, we can have but very loose ideas regarding the 
capacity of our public domain for supporting human life. 
As the result of a tolerably careful examination, but not a thorough survey, it has 
been estimated that, without the use of reservoirs, Colorado contains 7,323 square miles 
of irrigable land, or 7 per cent, of the area of the State. By storing the surplus water 
from the spring floods this area can be increased to 10 per cent, at least. 
Of the area of Utah. Major Powell estimates that 2.8 per cent, are irrigable without 
reservoirs. This estimate is based upon an assumed duty of but 100 acres per second- 
foot. Believing that this duty is but oue-half of what can be reached, we are inclined 
to increase his estimate to nearly double this :i mount, and to place it at 5 per cent. 
The use of reservoirs will not greatly increase this amount, as most of the available 
land can be served by the streams directly. It is probable that not more than (3 per 
cent, can be irrigated by the employment of reservoirs. 
In California it has been show n by survey that practically all of the great valley 
can be brought under irrigation. Add to this area of 15,000 square miles the numerous , 
valleys of the Coast Range, and of the San Bernardino Mountains, and the total arable 
area of the arid portion of the State will exceed 20, 000 square, miles. 
Judging from the character and size of the streams and the surface of the country, 
about 5 per cent, of the area of New Mexico is irrigable, and of 'Arizona about the 
same proportion. Wyoming, fully as well watered as Colorado, and having an im- 
mense area of plains, should have as great an area of irrigable land in proportion to 
its size. 
Montana has probably very nearly the same proportion, though the great stretch of 
arid plains in its eastern half would reduce it some what. A safe estimate of its arable 
area would be 8 per cent. Idaho has a slightly smaller proportional area than Montana, 
but greater than Utah. Probably 7 per cent, is a safe estimate. Nevada has compar- 
atively little water, it is safe to say not more than enough to irrigate 3 per cent, of its 
area. 
Of Oregon, east of the Cascade Range and south of the Blue Mountains, which is 
the portion requiring irrigation, probably 6 per cent, can be watered. It is claimed 
that irrigation is unnecessary in any part of Washington Territory. Whether this be 
true or not, will soon be determined. We are inclined to doubt whether the eastern 
part can be cultivated, with safety, without water at hand to supply the deficiencies 
<of the heavens. 
Of that portion of Dakota lying within the arid rogion, probably not more than 5 
