23 
those drawing water directly from the river, must in a general way 
grow crops whose needs for water vary somewhat as the stage of the 
river. 
Hence there cannot be a large acreage of crops needing late 
water without danger of loss. As the late crops are the most profit¬ 
able, there is a strong temptation to run some risk, especially as 
the water in early summer is usually in excess of the needs of that 
period. 
Some of the crops do not secure all the water needed. At pres¬ 
ent it is not possible to determine how much. Some water runs to 
waste which is counted in the amount entering the valley. There 
is a rough balancing between the two, and while the results are not 
so accurate as desired, with these facts in view they will not be mis¬ 
leading and will be useful as a preliminary estimate. It is hoped 
by the end of another year, by placing a register at the mouth of 
the Poudre, to have a more defintte knowledge of the amount 
which is not‘Used. 
Most of the valley under consideration is retentive of moisture. 
The crops are the cereals, alfalfa and clover, and especially toward 
the lower end of the valley, potatoes. The rainfall from 12 years 
observations at Fort Collins, which is some twelve miles from the 
gauging station, and about four from the foothills, is 13.80 inches 
per year. Observations have not been continued at other points in 
the valley for a period long enough to determine the rainfall, but 
from the record of two years it seems probable that the average is 
slightly greater than at Fort Collins. 
Table I. gives the average rainfall for the irrigated area, as de¬ 
duced from the reports of a number of observers who have kindly 
co-operated by taking observations of precipitation. 
Table I. also gives the total amount of water which entered the 
valley at the gauging station, and shows the number of acres 
w'hich would be covered to a depth of one foot. 
