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



canals, but when the supply becomes short some system of rotation 

 between sections of the canal is instituted. The exception is the 

 North Poudre Canal, which delivers on demand an allotment of 

 water made at the beginning of the season. Under certain restric- 

 tions, reservoir water handled by ditches as carriers only is delivered 

 on demand. Descriptions of some of the delivery systems of the 

 canals of the valley are given in later sections of this report. 



Maintenance problems in the valley present no new difficulties and 

 on the whole give less trouble than might be expected. The Cache la 

 Poudre is comparatively free from silt and sand, and deposits in 

 canals are usually limited to short stretches at the head and at 

 curves. These deposits are removed Avith scrapers in the spring or 

 fall. Canal grades which were proper for the original canals were 

 too heavy when these canals were enlarged, and at one time there was 

 much erosion of banks and bottoms, but this condition has been cor- 

 rected by the construction of checks or drops at proper points. For 

 local erosion brush mattresses and rock riprapping are used, as 

 shown in Plate VIII, figure 2. For river protection, rock riprap or 

 rock-filled cribs, as showm in Plate IX, figure 1, are used. Breaks 

 occur occasionally and are repaired in the ordinary manner with 

 scrapers, care being taken to secure a good bond between the old and 

 new material, to pack the new material carefully, and to raise the 

 water on the new section as slowly as the necessity for water will 

 warrant. The clear water and hot sunshine are favorable to the 

 growth of moss, and by the first of July it begins to cause trouble on 

 many of the canals. A moss-filled ditch is shown in Plate IX, figure 

 2. So far no successful method has been devised to prevent its 

 growth or to remove it. Generally it is allowjed to grow until it 

 almost chokes the canal. The water is then cut out of the canal and 

 the moss allowed to dry for two or three days. This helps to a cer- 

 tain extent', but is not a solution of the problem. Winter conditions 

 have to be contended with by only two or three canals carrying 

 water for storage in reservoirs. The winter supply rarely exceeds 

 100 second-feet, and little trouble is experienced in handling it. 



LARIMER & WELD CANAL. 



Early in 1879 the Larimer & Weld Irrigation Co. was incorporated 

 with a capital stock of $200,000 to take over the construction of the 

 Larimer & Weld Canal, on which construction work had been begun 

 in 1878, and to sell water rights. The water-right contracts pro- 

 vided that when rights to the capacity of the canal had been sold, 

 4 shares of the capital stock of the company were to be turned over 

 to the holder of each right so that control of the company would 

 pass to the owners of rights. After 366 rights had been disposed of 

 the owners of rights felt that the capacity of the canal had been 



