CONCLUSIONS. 
1. The mountain streams in the early irrigation season are largely 
supplied by melting snow. 
2. There is a marked diurnal fluctuation, greater with high water 
than with low, due to the daily variation in the rate of melting. 
3. The stream at high water may be one-half greater than at low 
water on the same day. 
4. Cloudy weather in the mountains, protecting the snow from 
the radiation of the sun, causes the fluctuation to disappear and the 
flow to decrease. 
5. This decrease is so great that the cloudiness associated with 
continued rain usually more than counterbalances the gain from the 
rain. 
6. The loss of snow by evaporation is considerable, especially 
when exposed to winds. 
7. Snow remains in the timber and in protected spots much 
longer than where exposed. 
8. This is due not so much to drifting as to shelter from the radia¬ 
tion afforded by the forest cover. 
9. Hence, the greater amount of forest cover the less violent the 
daily fluctuation, the more uniform the flow throughout the day and 
throughout the season, and the later the stream maintains its flow. 
10. The loss of the forest cover means more violent fluctuation 
during the day, greater difficulty in regulating the headgates and keep¬ 
ing a uniform flow in ditches and hence an additional difficulty in the 
economic distribution of water. Also the water runs off sooner, hence 
the streams drop earlier in the summer and on account of the lessen¬ 
ing of the springs, the smaller is the water flow. 
11. The preservation of the forest is an absolute necessity for 
the interest of irrigated agriculture. 
