2 BULLETIN 1026, U. S. DEPARTMENT OF AGRICULTURE. 



tion carried on for a number of years in the valley of the Cache la 

 Poudre River in northern Colorado are herein presented in the hope 

 that they will afford an opportunity for other communities possess- 

 ing less experience to benefit by the principles and practice so success- 

 fully worked out in the Poudre River basin. 



The investigation was carried on under a cooperative agreement 

 between the Agricultural Experiment Station of Colorado and the 

 Bureau of Public Roads, each party contributing equal amounts to 

 the undertaking. At first the investigation was in direct charge of 

 V. M. Cone, irrigation engineer, who, under the general direc- 

 tion and supervision of Samuel Fortier, Chief of the Division of 

 Irrigation Investigations, planned and carried out the work during 

 the years 1916 and 1917. Mr. Cone resigned to enter private prac"^ 

 tice in February, 1918, and Ralph L. Parshall succeeded him as the 

 representative of the bureau in Colorado. Since the writer, however, 

 had been intimately connected with the investigation from the be- 

 ginning, it fell to his lot to complete the work and write the report, 



CACHE LA POUDRE VALLEY. 



The Cache la Poudre River drains an area of approximately 1,900 

 square miles in north-central Colorado. The main stream heads 

 m Chambers Lake, a few miles east of the crest of the Medicine Bow 

 Range, and flows in a fairly straight line to its junction with the 

 South Platte River, 60 miles southeast. With its tributaries it drains 

 slopes of the Laramie, Medicine Bow, and Snowy Mountains. About 

 30 miles east of Chambers Lake the river breaks through the last 

 line of foothills and flows out on the plains. This line of foothills 

 forms a natural division and breaks the basin into two distinct parts. 

 West of the foothills the country is all rough and mountainous and 

 lies at an altitude of from 6,000 to 14,000 feet. Irrigation in this sec- 

 tion of the basin is confined almost entirely to forage crops in nar- 

 row strips along the streams. East of the foothills the valley proper 

 rarely exceeds a mile or two in width and is 50 to 100 feet below 

 the level of the adjacent land. In this section, and south of the 

 river, the bluffs are rather abrupt and are only a short distance from 

 the divide between the Cache la Poudre and Big Thompson basins, 

 thus limiting irrigation to the river bottoms and a small area of 

 bench land southwest of Fort Collins. 



North- of the river a rolling prairie, rising gradually from the 

 first bench, extends northward to the Wyoming line, and in this sec- 

 tion are located the larger canals and at least 80 per cent of the irri- 

 gated land in the basin. The altitude of the eastern division of the 

 basin ranges from 4,500 to 5,500 feet. 



