28 BULLETIN 82. 
THE CHANGES EFFECTED IN THE WATER USED IN IRRIGATION. 
§ 54. It seems proper to take up this subject before we pre¬ 
sent that of the return waters. The changes produced will depend 
upon the character of the soil irrigated and will probably differ in 
the case of sod-covered land and in that of land under cultivation. 
§ 55. The facts recorded in the preceding paragraphs relative 
to the changes, which took place during storage for the compar¬ 
atively short period of one season, clearly indicate that the only 
proper basis from which to start would be Poudre water taken for 
direct irrigation and a perfectly typical soil. These conditions 
might have been met but it would have been with difficulty. 
§ 56. The first series of samples taken for the purpose of 
studying the changes in the composition of the water used in irri¬ 
gation was taken in 1898, the second in 1899, and the third in 
1900, when I availed myself of the opportunity offered by an ex¬ 
ceptionally heavy and protracted rainfall whereby the water plane, 
as indicated by the hight of the water in the wells dug in differ¬ 
ent parts of the plot, was raised to within from 1.0 foot to 0.3 of a 
foot of the surface. The water in this case being rain water, or 
water produced by snow melting on the ground, eliminated the 
question of its composition. 
§ 57. The water which I used in the following experiments 
in 1899 was Poudre water mixed with some seepage, but the plot 
of ground was not typically good soil but rather an alkali soil. 
Originally this soil was in a bad condition, but it had been im¬ 
proved by cultivation at the time this experiment was made and a 
part of it was then in excellent condition. The results therefore 
may represent those of actual practice more nearly than if the 
whole plot had been in the very best condition, but it clearly in¬ 
volves the question of alkali. It is a difficult matter to find any 
land where the drainage is not perfect which is entirely free from 
this question, especially when considered from a chemical stand¬ 
point. The instances of Terry and Windsor lakes accumulating 
in a single season 27,127 and 18,894 tons of salts respectively, after 
having been in use as storage reservoirs for at least 12 years, is 
suggestive of a goodly supply, particularly when we consider the 
comparatively small area from which these quantities of salts were 
collected. 
§ 58. In 1898 the only water at my disposal was seepage 
water and the supply of this was limited. The water plane was 
moderately low and was raised from one to two feet in different 
parts of the plot. The water in the wells obtained its maximum 
hight in from one to five days and then fell, at first rapidly, after¬ 
wards gradually, until it reached the lowest point for the season— 
the maximum fall being 4.3 feet. The changes in the water will 
be evident from the following analyses: 
