2,645. These counts were usually made between mid May and Late July, 

 and represent the preater ma;iority of but not all of the fish that pass 

 above the dem. The peak of the spring chinook run is reached in June. 

 In 1944 and 1947 observations were also made on the fall runs passing 

 over the dam, and counts of 51 chinook and 774 silver salmon were obtained 

 in 1944, and 29 chinook and 1943 silver salmon in 1947. The peak of the 

 silver salmon run was reached in early October, the largest daily count 

 in 1947 being 144 fish on October 4tho 



The main hazard to fish life in this upper section is the reduction 

 in river flow, owing to storage of water in the reservoirs, during the fall 

 and winter months. This can, of course, seriously interfere with any 

 existing spawning activities of salmon, and frequently results in the loss 

 of eggs already deposited. 



Some spawning area is present above Easton Dam, but is virtually 

 unused by anadromous fish. Although the dam is provided with a fish 

 ladder, it has a relatively high gradient and several other faults and 

 consequently very few fish ascend the ladder. Easton Dam is in effect, 

 therefore the upstream limit of anadromous fish migration in the Yakima 

 River. 



The individual dams and diversions on the main Yakima are discussed 

 briefly in the following paragraphs.) 



Richland or Horn Rapids Diversion Dam is located 18 miles upstream 

 from the mouth of the Yakima River. It is of timber construction, 600 

 feet in length, and drops in 4 steps, each approximately 15 to 18 inches 

 in height, with 4 to 6 foot wide aprons between the drops. These aprons 

 prevent fish from jumping over the dam during low waters periods when 

 there is very little flow, but fish can easily pass over the structure 

 during periods of high water. In recent years two fish ladders have 

 been built, one near the center and one at the north end of the dam. 



Flash boards are used occasionally during the irrigation season, and 

 on at least one occasion even the fish ladders were found to have been 

 boarded up, a practice that should not be permitted in the future o 



Columbia or Kennewick Ditch takes off at the south end of the 

 Richland Dam. This irrigation canal has a c&pacity of 325 CefoSo, and 

 was screened in 1938 » 



Richland Ditch takes off at the north end of the Richland Dam, and 

 has a capacity of 300 c.f oS» It was ^screened in 1938o 



Kiona Ditch takes off on the north bank of the Yakima River 38 miles 

 upstream. It has a capacity of 40 cof.Soj, and was screened at a point 

 1 mile below the head of the ditch in 1938o The screen by-pass leads 

 to a slough-like side channel on the main river. 



Gibbon Station Diversion Ditch takes off on the south bank approxi- 

 mate ly~35~mrTes~upstreamI 



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