Control procedures 



Control de-vices may have to be installed on I9U ot* more streams 

 between the Tahquamenon River and the Michigan -Wisconsin border. Tenta- 

 tive sites have been located on the majority of the streams, subject to 

 change as warranted by conditions on individual streams and future 

 developments of control devices » 



The majority of streams in possible need of control are small (S to 

 l5 feet in width) . A considerable number are in the l5= to 35- foot 

 class. However, at least 57 are large or very large (tables 1-22). 



Electrical devices have been recommended for 65 streams which are 

 too large for mechanical weirs or barrier dams or in which good sites 

 for such devices are lacking. Many of these sites are some distance 

 (several miles') from the nearest power lines. Mechanical weirs are 

 recommended for 6I streams ^ although it is possible that this type of 

 device will be discarded in favor of more practical structures on 

 individual streams (Applegate and Smithy 195l) . 



Barrier dams are recommended for 68 streams, many of which are 

 difficult of access. Most of these streams are located in Ontonagan 

 and Gogebic Counties, Banks are ravine-like and the substratum at 

 the potential barrier sites is bedrock. Gradients are generally steepi 

 it is believed that mechanical weirs would be difficult or impossible 

 to hold due to the sudden rises in water levels following heavy rains. 

 A number of these barrier dams can be constructed on bedrock out- 

 croppings which are already partial barriers. 



Beyond the usual engineering problems accompanying the installa- 

 tion of control devices, the main problem to be faced in the Lake 

 Superior basin is that of relative inaccessibility. Many potential 

 control sites are miles from the nearest roads,, and can be reached 

 only by compass course through rugged areas often covered with almost 

 impenetrable slash and second growth. 



The control program in Lake Superior logically should be initiated 

 by constructing ccntrol devices in those watersheds in which adult sea 

 lampreys, nests, or sea lamprey larvae have already been observed. At 

 the close of the 1951 season these watersheds numbered l5. At the 

 recommended control sites, the main streams of eleven of these watersheds 

 are large, three are of moderate size, and one is small. Details con- 

 cerning utilization in these particular streams are presented in 

 table 23. 



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