IE. North Fork, Salmon River , — (Inspected July 10, 19iil; 

 Parkhurst and Zimraer,) The North Fork enters the main Salmon River 

 approximately 229 miles above the raouth« The stream is about 23 

 miles longo Near the mouth it was 3U feet wide, discharging about 

 80 Cef.s, and the water temperature was 55«0°F« The gradient is 

 moderate to fairly steep. The water was extremely muddy for a dis- 

 tance of 17 miles above the mouth* Above this point the stream was too 

 small and steep to be of value to salip.on» '^he extrone turbidity was 

 due to a large gold mine at Gibbonsville, 11 miles above tJie mouth, 

 and a number of smaller mining operations at various points along the 

 stream. Under natural conditions the stream contained a fair amount 

 of suitable spawning area, but the stream bed had become so heavily 

 silted as a result of mining activity that it was of no value to 

 salmon at the time of the survey. The North Fork originally support- 

 ed a run of chinook salmon, but it was reported that no salmon had 

 been seen in it for man3r years a 



IF, Lemhi River , — (June 30 - July 8, 19Ulj Parkhurst and 

 Zimmere) The Lemhi River enters the Salmon River at Salmon, Idaho, 

 appro:cimately 2^1 miles above the mouth. The stream is about 6o 

 miles long. Near the mouth it was 32 feet wide, discharging about 

 15 c.f.s, and. the water temperature was 59oO°F,, most of the flow 

 being diverted, ^he gradient is moderate throughout. Spawning area 

 is abundant, of excellent quality, ?nd well distributed. There were 

 880,000 sq, yd, of s ui table spawning area, constituting approximately 

 59 percent of the total bottom. 



The Idaho Power Company maintains a diversion dam 6 feet 

 in height at a point 1 mile above the mouth of the river. This dam 

 is not equipped with fishways, and is a barrier to salmon except 

 during the June high water stage, when a few early-arriving chinook 

 salmon succeed in passing it. During low water periods the entire 

 flow is diverted except for seepage. At the time of observation the 

 dam was impassable to fish, and was diverting 312 c,f,s, into the 

 canal leading to the power plant. The diversion is not equipped 

 with any fish protective devices. The tailrace discharges into the 

 main Salmon River less than 1/2 mile below the power plant, and a 

 short distance below the mouth of the Leralai River, Since this diver- 

 sion takes almost the entire flow during the time ^vhen most of the 

 salmon should be entering the stream, the majority of these fish as- 

 cend the tailrace to the power plant, where they are completely ob- 

 structed. The turbines operate under a 38 foot head. They are the 

 low speed, reaction type, and probably do not greatly injure the 

 downstream migrants. 



There is an irrigation diversion located about 3 miles 

 above the mouth which was withdrawing about 20 c,f,s, at the time 

 of observation. The dam in connection with this diversion is on a 

 side channel and is not a barrier to fish, 



^ere is aii irrigation dam 3 feet in height located 7^ miles 

 above the mouth. No fishway is provided and the dam is a barrier at 

 low water. The ditch was withdrawing about 30 cf.s. 



26 



