would then come through two ports in the base, where it is controlled 

 by two slide-type sluice gates. The average momentary discharge is 

 75 c.f.s. This dam is a total barrier to fish. Its purpose is to 

 maintain a water storage reservoir in order to provide supplemental 

 irrigation for approximately 6,000 acres in the Lower Powder Valley. 

 The reservoir has a capacity of 17,U00 acre-feet. It covers a sur- 

 face area of 750 acres, and extends for about 3 miles above the dam. 

 It was reported by the dam tenders and other reliable persons that 

 "Silverside" salmon and steelhead trout ascended the stream and con- 

 gregated at the base of the spillway in each of several successive 

 years after the completion of the dam, and that a large number of 

 these fish were captured here by people who became aware of this 

 condition. The dam tenders reported that no salmon or steelhead had 

 been seen at the base of the dam for several years, the runs to the 

 headwaters evidently having been exterminated. 



The Powder River extends for a distance of approximately 28 

 miles through the broad, flat Baker Valley above the Thief Valley 

 Canyon. The discharge was 107 c.f.s. above the North Powder River 

 confluence on July 5, 19^2, but the flow becomes greatly diminished 

 during the late summer and fall irrigation season. The water tem- 

 perature was over 70 F. throughout this section. The gradient is 

 very slight, and the stream bed is composed almost entirely of mud 

 and silt, with no suitable salmon spawning area. One arm of the 

 stream meanders down the east side of the valley for a distaaice of 

 10 miles in a section known as Baldock Slough. A number of small 

 irrigation ditches lead from this slo\igh, serving the east side of 

 Baker Valley and the lower Sunnyslope District. There are a ntmiber of 

 small, open irrigation ditches in the Baker Valley section, in addition 

 to several larger, more important installations. Most of the ditches 

 were dry or flowing less than 1 c.f.s. at the time of observation, 

 being used mainly for stock water at that season. 



The Estes Irrigation Diversion Dam is located k miles below 

 the town of Baker, or approximately 8l miles above the mouth of the 

 river. This dam is k feet high and 36 feet long. It had no spill 

 over the crest, the water seeping through and under it, and must be 

 considered a barrier to fish. The ditch is 5? feet wide at the head- 

 gate and was withdrawing less than J c.f.s. It was reported that 

 the ditch would be cleaned out in the fall emd would have a much 

 larger flow during the irrigation season. 



There is another similar low irrigation diversion dam 300 

 yards above the Estes Dam. The height of this dam varies with the 

 use of stop-logs and flash-boards. It may be a barrier to fish at 

 certain seasons. The foundation is permanently constructed, with a 

 concrete apron extending I5 feet downstream. The ditches at each 

 end of the dam are of small size and without headgates. They were 

 completely dry, and have a capacity of only a few second-feet during 

 the season of maximum use. 



7^ 



