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 with 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 shown 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 allowed 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 
