72 BULLETIX 1026, U. S. DEPAETMEXT OF AGRICULTUEE, 



not considered necessary. The few that have been provided are 

 simple makeshifts, usually depressions a foot or two above high 

 water line which are left without embankment. The few dams in 

 stream beds are of course properly equipped with spillways. 



Outlets are either lines of tile or iron pipe or conduits of masonry 

 or concrete. The pipe lines are all laid in concrete and are provided 

 with concrete collars to cut off seepage. The masonry conduits are 

 generally embedded in concrete and rest on solid foundations of 

 concrete or masonry and concrete from 1| to 5 feet in thickness. 

 Gate wells are ordinarily at the top of the inner slope, as gates set 

 either at the upper or lower end of the conduit have proved to be 

 less satisfactory^ Plate XYII, figure 2, shows the gate tower of the 

 North Poudre Keservoir No. 15 blasted out after it had been replaced 

 by a well within the dam as shown. The was done as a matter of 

 precaution upon order of the State engineer after a similar structure 

 in Lake Loveland had been destroyed by ice pressure. Many of 

 the reservoirs have no gate wells, the gate stem being brought up 

 through the dam in 4 or 6 inch cast iron pipe. Gates are of various 

 types, including iron-strapped wooden gates, sliding iron gates, and 

 other more pretentious valves. Lifting devices are all some standard 

 combination of screw and lever. 



The total capacity of the reservoirs of the valley is over 150,000 

 acre-feet. The largest is the Windsor Eeservoir, which holds be- 

 tween 17,000 and 18,000 acre-feet, and from this size they range down- 

 ward to many which hold less than 5 acre-feet. Some have never 

 been surveyed to determine their capacities, and little dependence 

 can be placed in the capacity tables of a majority of those which 

 have been surveyed. The work was often done in such a manner 

 that errors show on the face of the table, indicating in one case that 

 the reservoir far a few feet of its depth took the shape of an hour- 

 glass. It is believed that accurate capacity tables based on reliable 

 surveys would aid materially in the operation of the canals carry- 

 ing reservoir water and would eliminate to a great extent in- 

 equalities in exchanges and in the distribution as well. 



The very low first cost of the majority of reservoirs in the valley 

 is indicated by the figures shown in Table 28, which, with the 

 exception of the average, are reproduced from a bulletin by C. E. 

 Tait, issued by the IT. S. Department of Agriculture in 1903.^° The 

 Fossil Creek and Cache la Poudre Reservoirs run much above the 

 average for the reason that each required a high and long dam 

 across a valley. The sites of North Poudre No. 2, North Poudre 

 No. 3, and Coal Creek Reservoir were developed at such a low cost 

 because they were natural basins requiring only an outlet in a cut 



"> storage of Water on Cache la Poudre and Big Thompson Rivers, by C. E. Tait, V. S. 

 Dept. Agri., O. E. S. Bui. 134. 



