IRRIGATION IN NORTHERN COLORADO. 23 
Almost without exception the distribution is made in strict ac- 
cordance with appropriations and priorities. Little attention is paid 
to the small ditches above the mouth of the canyon or at the head of 
tributaries entering below the canyon. The general feeling is that 
irrigation from these small ditches does not affect to any great ex- 
tent the total supply of water available below, except possibly in 
very dry years, and that the trouble and expense of keeping track of 
them would more than counterbalance any good which might result. 
Below the canyon on the main stream a few small ditches divert prac- 
tically at will on early excessive decrees, but the greater part of this 
water is wasted directly back to the river and the total supply is 
diminished by only a small amount. Another exception is the prac- 
tice of allowing some canals to " accumulate " water for a few days. 
For instance, the appropriation of 175 second-feet of the Larimer 
County Canal No. 2 usually fails about July 10, and instead of al- 
lowing the canal to draw a varying and dwindling head for perhaps 
10 days, it is permitted to draw a good head for 3 or 4 days and is then 
cut off entirely. By general consent certain exceptions which work 
out to the best advantage are made in the case of reservoirs. The 
Cache la Poudre and the Fossil Creek Reservoirs have first call on 
the water which heretofore passed through the Mason and Hottel 
mill race and they may be filled slowly with the assurance that they 
can be topped out when the spring flood comes down. The filling of 
Claymore Lake may also be delayed with the assurance that it can 
be completely filled in a week during the flood period. So during a 
part of the storage season water which might be demanded by these 
reservoirs may be diverted to others which have less chance of filling 
either on account of late priorities or small intakes. 
DIVERSIONS FROM THE RIVER IN 1916 AND 1917. 
Diversions from the river for the 2 years of the investigation are 
shown in Tables 7 and 8 and figure 3. The ratio of diversions for 
storage to the total diversion was 14 per cent in 1916 and 20 per cent 
in 1917, but in neither year was the total available storage capacity 
used. These figures do not include storage in the mountain reservoirs 
of the basin, but were these included the figures would not be changed 
greatly. 
Diversions for direct irrigation begin in April and continue until 
the first part of October, though the greater part of the demand is 
from April 15 to September 15. Water for storage is drawn through- 
out the year except in August, but practically all the water stored be- 
tween June 15 and the end of the season is foreign water or " Wind- 
sor exchange." The large amount of storage in April and May, 1917, 
is accounted for by a high river and heavy rains which decreased the 
demand for water for direct irrigation. 
