russell] SURFACE STREAMS. 15V) 
condition, and the one that controls not only agriculture, but settle- 
ment for any object, is the prevalent scarcity of water. Under these 
conditions, water is more valuable than land. In fact, land, however 
well situated and however rich, is valueless for farming purposes 
unless water can be brought to it. 
The water available for irrigation may be conveniently classified 
under three heads, namely, surface streams, springs, and wells. 
Direct precipitation, averaging as it does less than 3 inches during the 
growing season, is too small to permit successful agriculture without 
irrigation, except, possibly, in certain localities where the soil is of 
such nature as to absorb and retain the winter supply. 
SURFACE STREAMS. 
The greatest source of water supply for the Snake River Plains, and 
the one first to be utilized, is to be found in the streams which, rising 
in the neighboring mountains, flow to or across them. The quantity of 
water reaching the plains in this manner and the various wa}'s it can be 
most economical ly diverted and used for irrigation have been investi- 
gated by the State engineer of Idaho, and the conditions existing are 
described and discussed in a series of reports. One of these, the biennial 
report for the years 1899 and 1900, by D. W. Ross/' is remarkable for its 
breadth of view and thoroughness, and will prove invaluable not only 
to individuals and companies directly interested in irrigation, but 
should serve as a guide to the legislature of Idaho in framing wise 
laws to govern the uses to be made of the scant water supply. 
The central plain of southern Idaho has an extent of about 20,000 
square miles. The surface streams available for irrigating this great 
tract are Snake River and its tributaries, together with the "lost 
rivers " which fail to reach the main drainage channel. While consider- 
able portions of the plains are rocky and entirely unsuited for agri- 
culture, and other portions, also large, are too high above the streams 
to be irrigated, there remains more good land which can be reached 
by canals than can be brought under cultivation by the use of the 
water carried by all the streams during the growing season. 
All of the smaller streams that reach the Snake River Plains from 
either the north or south have been fully utilized, except the Bruneau 
River, which in summer still discharges about 400 cubic feet per second 
into Snake River. The waters of Snake River above American Falls 
are largely utilized, about 211,000 acres being irrigated, of which 
about 200, ooo acres are in the valley proper. The great waste of 
water that accompanies the irrigation of this land is forcibly stated b}^ 
Ross. In spite of the large demands made on Snake River in the 
n Biennial Report of the State Engineer to the Governor of Idaho for the year 1899-1900; [Boise] 1901, 
pp. 1-101, 6 plates and 3 maps. 
