THE IRRIGATION AGE. 



147 



The Terrace Reservoir in the San Luis Valley, Colorado. 



W. A. Anderson. 



In the southwestern portion of the San Luis valley 

 a great feat of hydraulic engineering is being under- 

 taken in the construction of the Terrace reservoir. The 

 enterprise will mean the reclamation of more than 

 twenty thousand acres which are now virgin soil. 



The reservoir is situated in the foothills about 

 twenty-five miles southwest of Monte Vista and some 

 eighteen miles west of Alamosa. The water is taken 

 from the Alamosa river, or more correctly the basin is 

 to impound the flood waters of that stream and use it 

 for irrigation purposes. Some idea of the magnitude 



ting canal until it has reached a point some miles below 

 the reservoir. It is there that the headgates of the 

 main ditch are located. While the headgates are well 

 away from the foothills, the country along the main 

 ditch is rolling for many years and has necessitated the 

 construction of several costly flumes. Last fall the 

 company completed negotiations for the purchase of 

 practically all the water rights along the Alamosa river 

 at a price of $50,000. Thus the company has prac- 

 tically no priorities to fear should a scarcity of water 

 ever occur. 



View of the Gunbarrel Road from the Hotel Grand, Monte Vista. 



of the enterprise can be had from the fact that before 

 the dam is completed the enterprise will have cost 

 $650,000, about half of which has already been ex- 

 pended. 



The dam itself is to be the largest hydraulic filled 

 dam in the world, so far as is known. When completed 

 it will have a height of two hundred and twelve feet (or 

 more exactly, two hundred and eleven and six tenths 

 feet). When work was stopped in the fall of 1907 

 about one hundred and fifteen feet had been filled. The 



To return to the reservoir. Water for the hydraulic 

 power is brought a distance of nine miles down the 

 river, and it is not difficult to imagine the immense 

 power which it has when it is poured through the moni- 

 tor heads. This power ditch alone cost the company some 

 $75,000 for construction. The water directed from the 

 monitor heads washes down the gravel and soil of the 

 surrounding hills and directs them into a sluice whence 

 they are forced onto the dam. 



Near what will be the center of the dam when it 



Dam of Terrace Reservoir When Work Was Stopped for the Winter in the Fall of 1907. 



fill is being made in a deep gorge cut by the Alamosa 

 river. In order to utilize this gorge it was necessary 

 before any filling was done to change the course of the 

 river. This was done by cutting a tunnel through three 

 hundred yards of the solid rock forming the northwest 

 wall of the gorge. In this tunnel are placed the valves 

 which are to control the flow of water from the reser- 

 voir, for it is through the tunnel that the waters of the 

 reservoir are to be handled. When the water has passed 

 through the tunnel it is diverted back to the main 

 bed of the stream and is not taken into an irriga- 



is completed is a great cement core, which is set down 

 to the solid rock on each side of the gorge. This core 

 cost $30,000 and when the dam is filled it will be 

 totally covered. It is estimated that when the reser- 

 voir is completed ami filled to its full capacity of 33,000 

 acre feet of water it will be a great lake extending 

 back a distance of seven miles. It has been suggested, 

 and is well within the range of possibilities, that some 

 day on the banks of the lake formed by the impound- 

 ing of the flood waters of the Aiamosa, a summer re- 

 sort may be located. No more picturesque or beautiful 



