lERIGATIOlSr IN I^OBTHERIsr COLORADO. 29 



are found. Almost without exception they are designed or installed 

 so that accurate measurements in them are almost impossible. In 

 Plate IV, figure 2, is shown a flume or chute carrying water from 

 Long Pond to the Larimer and Weld Canal and Lindenmeier Lake. 



In the original construction of the canals of the valley contours 

 were followed closely and only a few drops were necessary. These 

 are generally of fair design and well constructed. A drop on the 

 North Poudre system is shown in Plate V, figure 1, and in Plate V, 

 figure 2, is shown a drop- at the tail of a south-side ditch. Some of 

 the canals with slightly excessive grades have been corrected by the 

 construction of timber or concrete checks, in which part of the con- 

 trol is by flashboards. A typical check is shown in Plate VI, figure 1. 



Laterals receive their supply from the main ditch through lines 

 of tile ranging in diameter up to 24 inches. The upper end of the 

 tile is set in a concrete bulkhead, and the flow through the pipe is 

 controlled by an iron gate sliding in grooves in an iron framework 

 which fits over the end of the tile. The gate stem is threaded, and 

 the regulation is by one or two wheels working on these threads and 

 against crosspieces. This gate is the Powell gate, so-called after its 

 designer, B. F. Powell, of Eocky Ford.^ 



The most common device for measuring water to laterals is the 

 rectangular weir which is found in sizes ranging from 1^ to 10 feet 

 in length of crest. The installation of these weirs is usually faulty, 

 and the most accurate measurements can not be obtained with them. 

 Bottom and end constructions are usually deficient, and entrance 

 velocities are almost invariably too high. A combined weir and 

 drop on a lateral of the Larimer County Canal is shown in Plate VI, 

 figure 2. Division boxes are also very common for the distribution 

 of water in small canals and laterals. Where an overfall is pro- 

 vided the division is fairly good, but otherwise it may or may not 

 be. Typical division boxes are shown in Plate VII. The device 

 used by the Pleasant Valley and Lake Canal for measuring water 

 to users is shown in Plate VIII, figure 1. The crest of the weir is 

 4 inches above the bottom of the box, and the depth over the crest 

 is measured on a plug about a foot back from the weir. The slots 

 in the sides are intended for 2 by 12 inch planks, which are supposed 

 to float in the slots and act as baffles. 



With few exceptions, all lateral headgates and measuring devices 

 are under the exclusive control of the canal company. Deliveries are 

 made at the head of the lateral, and the canal company disclaims all 

 responsibility for the distribution of water from the lateral and for 

 the maintenance of the lateral. A continuous delivery of a prorata 

 part of the flow is the method in common use on the majority of the 



^ A drawing of this gate appears on page 39 of O. E. S. Bulletin No. 229. 



