72 BULLETIN 1026, U. S. DEPARTMENT OE AGRICULTURE. 
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 1J 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 XVII, figure 2, shows the gate tower of the 
North Poudre Eeservoir No. 15 blasted out after it had been replaced 
by a well within the dam as shown.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 clam 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 for 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 U. S. Department of Agriculture in 1903. 10 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 Eeservoir were developed at such a low cost 
because they were natural basins requiring only an outlet in a cut 
10 Storage of Water on Cache la Poudre and Big Thompson Rivers, by C. E. Tait, U. S. 
Dept. Agri., O. E. S. Bui. 134. 
