IRRIGATION DIVERSION STUDY 



As early as 1893 the State Legislature showed concern in their 

 legislative enactments over the loss of fish in irrigation diversions. 

 Since that time various statements of fish loss have appeared in the 

 Department's biennial reports. This problem is and has been a real 

 one, but to date no clear cut answer has been provided to the prob- 

 lem. In Montana, fish screens of varying types have been placed in 

 the canals. None, from Montana's viewpoint, has been completely 

 satisfactory, and all are expensive, not only to install, but especially 

 to maintain. 



During the past biennium the Fish and Game Commission took a 

 forward step in authorizing a complete evaluation of the irrigation 

 diversion problem. The study was undertaken cooperatively with the 

 Montana State College Agricultural Experiment Station, and in order 

 to limit activities for the initial phase of the work so that real re- 

 sults might be had, the study was confined to the irrigation diversions 

 of the Gallatin Valley. Briefly tlie findings and recommendations are as 

 follows: 

 i. It has been demonstrated conclusively that fish losses to any one 



canal in the Gallatin Valley are small enough so that conventional 



type fish screens cannot be installed and maintained economically. 



2. If water flows into canals are shut off by a predesigned method, a 

 large proportion of the fish in the canals can be brought back to the 

 river. 



3. By altering the picture of cover, that is of overhanging brush, cut- 

 banks, and pools in the canals, fish may be brought back into the 

 river much more readily. 



4. The greater proportion of fish enter' canals with the initial flush 

 of water into these canals in the spring. It is recommended that, 

 where possible, irrigation headgate structures should be flushed 

 each spring prior to running water down the canal proper by di- 

 verting water from the canal through a by-pass structure and by- 

 pass canal back to the river. This will shift the fish population 

 from the headgate structure to a point in the river further down- 

 stream. 



5. It is clear that unless the problem of providing or insuring ade- 

 quate stream flows is faced objectively, no amount of effort to keep 

 fish out of irrigation canals will succeed. 



GRAYLING STUDY 



The grayling, once abundant in Montana and Michigan and other 

 portions of North America, has suffered more from the encroach- 

 ment of man than any other fresh water game fish. As man has ex- 

 tended himself and his cultural and economic system throughout the 

 nation, the grayling has retired from its indigenous haunts. While 

 the Arctic subspecies are common in Canada and Alaska, the sub- 

 species found in the United States has receded until Montana has the 

 only stocks in the nation with any degree of magnitude and stability. 



But even in Montana the grayling is not secure. Michigan, while 

 realizing that its grayling stocks were receding in abundance, felt a 



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