SPILLWAYS FOR RESERVOIRS AND CANALS. 9 
been built at Klamath Falls, Oreg. (fig. 1). The water spilled is 
diverted to the Link Eiver after it has been used to generate power. 
The fall from the canal to the river is 48 feet in a distance of about 
170 feet. The canal would not permit of a rise greater than 1 foot 
above flow line, because it was built along a steep side hill and it was 
impractical to construct the banks of sufficient height to allow of any 
considerable rise. The conditions required a structure capable of 
spilling the waste water resulting from the proper regulation of a 
power plant above the structure without at the same time causing an 
excessive rise in the canal flow line. The sudden closing down of the 
entire plant presented an emergency in which the entire flow had to 
be taken care of quickly without exceeding the limiting rise and fall 
of flow line. An overflow spillway crest to satisfy such demands 
with its safe coefficient of discharge was calculated to be about 200 
feet long, and to utilize as small a horizontal distance as possible was 
concentrated by indentations to a length of 61 feet as measured in a 
straight line along the canal bank. 
The principal reason for concentrating the over-all length of the 
spillway was to provide a wasteway channel through which the 
water would be conducted over the earthen slope to the river after 
flowing over the crest. A section 3 by 8 feet with the slope of the 
ground at the point was capable of taking care of the discharge after 
it had been collected, but the concentration of crest length was to 
reduce, as far as possible, the dimensions of the upper portion of the 
collecting channel and therefore the cost. 1 The structure only re- 
sulted in this saving, as the same length of spillway had to be pro- 
vided with consequent cost of construction. It is another example 
of the adaptabilit} 7 of the siphon spillway in cases where space and 
close regulation are paramount. 
SPILLWAY CONTROL. 
It may be desirable normally to carry the water near the maximum 
allowable level rather than sufficiently below that to provide for 
emergency flow. This is provided for by placing the permanent 
crest of the spillway sufficiently low to pass the maximum flow, 
and placing on top of this temporary or movable parts which will 
go out automatically or can be removed or adjusted in case of flood 
so as not to interfere with floating debris. The immediate removal 
of these barriers is of particular importance, because having provided 
an ample spillway it should be kept free of any obstruction and at 
all times ready for any sudden demands made upon it, regardless of 
other agencies which may be provided as additional facilities in 
effecting discharge. Inadequate satisfaction of these conditions has 
led to a great number of wrecked structures resulting in the loss of 
1 Description from an article in Engineering News, Sept. 9, 1909. 
