July, and is unscreened. The maximum capacity of the canal is 235 

 c.f.s. 



Above this point the river extends for lU miles through a 

 narrow, steep, rocky canyon to the Owyhee dam and reservoir, the 

 upper terminus of the survey,, There is almost no cultivation in 

 this section, except on several small terraces where there is some 

 hay and pasture. The stream bed has an average width of 120 feet 

 and a slight to moderate gradient. There are a fair number of 

 shallow riffles containing a considerable amount of spawning area 

 However, the stream was heavily silted, due to the turbid discharge 

 from Owyhee Dam There a^ numerous resting pools with slight stream 

 cover. The water temperature ranged from 67.£°F. at the lower end 

 of the canyon to ii7o0°F. at Owyhee Dam. 



There is a small irrigation dam and diversion about 16 miles 

 above the mouth. The unscreened ditch carries about 2 c.f.s. The 

 temporary, loose rock diversion dam is not a barrier to fish except 

 under low flow conditions. 



The Owyhee Dam, located approximately 26 miles above the mouth, 

 was completed by the U.S. Bureau of Reclamation in 1933o It is 

 primarily a storage dam for irrigation, and has been used exclusively 

 for that purpose. However, it was designed with penstock lines so 

 that it may be converted to produce hydro— electric power The dam 

 is 330 feet high, and is a total barrier to fish. The reservoir 

 extends 23 miles upstream At the time of observation the North Canal 

 diver son from the reservoir, running 70 miles northward, was carrying 1,000 

 c.f.s* The South Canal diversion at the same time was carrying l,li00- 

 1,500 c.f.s. a distance of 37 miles into Owyhee County in southern Idaho. 

 Sufficient discharge from the outlet gates is maintained to supply the 

 "Old Owyhee" diversion lU miles downstream, the discharge on the date of 

 observation being 207 c.f.s. However, there is usually an inadequate 

 flow for fish in the lower 12 miles from the Old Owyhee canal to the 

 mouth. Further, during the season of water impoundment from October 

 through March the entire stream bed below Owyhee Dam is mostly uncover- 

 ed. Gaging station records of the U.S. Geological Survey for the water 

 year 19U6-U7A taken at a station 3/ii mile below Owyhee Dam, show a 

 discharge of 8 c.f .s from October 6 through April 5. Under such flow 

 conditions the Owyhee is of no present value to anadromous fish. 



y 



U.S. Geological Survey, Surface Water Supply of the United States, 

 19u7. Part 13, Snake River Basin. Water-supply paper No. 1093. U.S. 

 Government Printing Office, Washington: 19^0. 



17 



