the terminus of the survey* Gaging-station records for the water- 

 year I9U0-UI (U.S.G.S. I9U2), taken at a station 12 miles above the 

 mouth, show discharges ranging frcn a maximum of 290 c.f .s, in March 

 to a minimuTi of U»l c.f.s, in October, During the survey the stream 

 was 12 feet wide at this point, and the flow ranged from 5»1 to 

 6.3 c.f.So The water temperature ranged from 70 to 82 Fo in the 

 lower 12 miles. In the upper part the water temperature declined to 

 1;9°F, at the terminus of the surveyo There are 2l|. water rights for 

 Mann Creek, and 20 irrigation diversions were found. Thirteen of the 

 dams associated with these diversions, as well as several falls and 

 log jams, were considered to be barriers at low water. Each of these 

 dams diverts practically the entire stream at that point during low 

 water stages, lea^/ing a dr;;r channel. Wherever a point downstream is 

 reached where the volijme of flow has been built up sufficiently by 

 irrigation returns, springs, and tributaries, another dam repeats the 

 process. 



It has been proposed that the U. S. Bureau of Reclamation build 

 a storage dam, to be known as the Spangler dam, at a point about lU 

 miles above the mouth. The plans call for an earth-fill structure 

 having a height of llB feet. It would be provided with an outlet 

 t-jnnel discharging under a head of U5 ft. No facilities are to be 

 provided for the upstream passage of migratory fish nor for the pro- 

 tection of downstream migrants. However, it has been recommended 

 that the project undertake to capture and transfer to other nearby 

 streams such migratory fish as may appear below the dam during the 

 first few years after its construction. 



There were 9,300 square yards of suitable spawning area, consti- 

 tuting approximately 6 percent of the total bottom in the portion sur- 

 veyed. Most of the suitable spa'';^ning was found in the upper part of 

 the stream, above the proposed Spangler dam, and is available only at 

 high water and only to steelhead trout. 



Reports indicate that many years ago Mann Creek supported good 

 runs of Chinook salnon and steelhead. The salmon run has been prac- 

 tically exterminated, and there remains only a small spring run of 

 steelhead, A few of these fish ascend several of the upper tribu- 

 taries, including 2A-(1) Adams Creek, 2A-(3) Fourth of July Creek, 

 2A-(U) Bitt Creek, and 2A-(5) Bear Creek, It was reported that they 

 do not enter 2A-(2) Stacy Creek, and probably not 2A-(3)a Porcupine Creek, 



The protection and rehabilitation of this small run of steelhead 

 would be doubtful of success because of the numerous existing dams and 

 diversions, and also because of the difficulties which would be en- 

 countered in the passage of both upstream and downstream migrants over 

 the proposed hi^ Spangler dam. The cost of a rehabilitation program 

 would also not be warranted by the results which might be achieved. 



36 



