Examination of streams in Minnesota 



Cook County ; Contains 77 separate iratersheds (Fig. h)» At least 

 I46 of these are unsiiitable for sea lamprey spawning because of the 

 following limiting factors: low temperatures, scouring, bottom 

 irregularity, barriers, small size, rapid fluctuations in water 

 levels, etc. 



Twenty-two streams are considered to be marginal (Table 3)» 

 Spawning gravel for a varying number of nests is present, but other 

 factors are likely to be unfavorable enough to seriously hamper 

 spawning efforts. 



Nine streams with productive potentials ranging frcsn me- 

 dium to large are believed to be quite suitable for sea lampreys, 

 despite the presence of limiting factors (Footnote 2, Table 3). 

 Six of these streams are large; three others averaged 5, 8j and l5 

 feet in width in the sections examined. Electrical control devices 

 are recommended for all of than. 



The geology and surface featvires of the Cook County water- 

 shed have been ctescribed in detail in a publication of the Minnesota 

 Department of Conservation (Sinith and Moyle, 19UU). Suffice it to 

 say that most of the streams in the Cook County watershed flow over 

 rocky, rugged terrain, often cliff-like in gradient. Barriers and 

 partial barriers to fish are numerous. Run-off is rapid and great 

 fluctuations in water levels are the rule. The majority of streams 

 is small. A number of them are probably intermittent in character. 



Any type of control operation will be aided ty the accese- 

 ibi].ity of the majority of streams in the watershed. A few streams 

 in the northern portion of the county are relatively inaccessible. 



Installation of electrical devices will be difficult in 

 the Pigeon and Arrowhead Rivers due to large size, reversing cur- 

 rents, shifting sand bars, and pulp wood operations. 



Lake County ; Contains 50 separate watersheds (Fig. 5). At least 

 13 of these are unsuitable for sea lamprey spawning because of the 

 presence of barriers, small size, irregularity of bottan, etc. 



Twenty-eight streams are considered to be marginal (Table U). 

 Spawning gravel for a varying number of nests is present, bat other 

 factors are likely to be unfavorable enou^ to Impede spawning efforts. 



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