16 BULLETIN 115, U. S. DEPARTMENT OF AGRICULTURE. 



JACKSON DITCH HEADING, COLORADO. 



The concrete and steel structure shown in Plate III, figure 2, was 

 constructed in 1909, 8 miles above Fort Collins, Colo., on the Cache 

 la Poudre River. A low diversion dam raises the river water high 

 enough to supply the demands of the Jackson Ditch, which carries 

 about 75 second-feet of water. The gate shutter is of sheet steel 

 operated by double rack stems, connected by a bar which turns both 

 pinions at once. In front of the slots for this gate is a set of auxiliary 

 slots for the insertion of flashboards in case it is necessary to remove 

 the steel gates for repairs during the operating season. This feature 

 can be adopted to advantage in many gates. The sand sluice adjoins 

 the ditch gate. The operators state that it works well but is supple- 

 mented by another sand gate a few rods below the diversion gate. 

 In other parts of the West an installation similar to this has been 

 more cheaply constructed by making the sand sluice merely a de- 

 pression in the diversion weir, controlled with flashboards, which 

 may be pulled during high water and replaced when the full height 

 of the weir is needed, which occurs at a time when less sand is running 

 in the stream. The total cost of the weir and gate structure was about 

 $600. The concrete was mixed by hand in a ratio of one part cement 

 to six parts of sand and gravel mixed. 



NAPESTA DITCH & RESERVOIR CO. HEADING, COLORADO. 



The heading of the Doyle Arroyo feeder of the Napesta Ditch & 

 Reservoir Co., located on Doyle Arroyo, in Pueblo County, Colo., is 

 out on the plains 24 miles below Pueblo (fig. 1). 



These arroyos in the vicinity of Pueblo are subject to sudden and 

 very violent rushes of water, being dry for months at a time and then 

 carrying a river of water for a short period. The only possible use of 

 such water from an irrigation standpoint is to divert a large head for 

 a short time and store the water in a reservoir. The object of this 

 heading was to divert 850 second-feet of water from a vertical-sided 

 wash, or arroyo as it is known locally. The sides and bottom of this 

 wash are in shale where there is little danger of seepage under the 

 structure, but it was necessary to protect the bottom of the wash 

 above and the canal below the gate by a concrete apron, as the water 

 was to be delivered under a head of several feet, through undershot 

 gates, where the resulting velocity and scour would be very heavy. 



There are no sand sluices in connection with this heading, as there 

 is little or no sancl in the water, but the water is very heavy with 

 adobe silt in suspension, which is carried on into the reservoir. 



As shown in figure 1, water is checked up by a low-diversion dam 

 extending across the arroyo. As the spring and flood flow of this 

 wash is estimated at 3,000 second-feet and it is only 50 feet wide, 



