Nine streams with productive potentials ranging from me- 

 dium to large are considered quite suitable for sea lampreys, 

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

 Five of these streams are large, frcmi 30 to 12^ feet in vddth in 

 the areas examined. The remaining U streams average frcm 7 to 20 

 feet in vddth. Electrical control devices are reccmmended for all 

 but the Gooseberry River, Control in this stream will be diffi- 

 cult due to its large size, and the presence of a reversing current 

 resulting from lake seiches. 



The geology, surface features, and stream characteristics 

 of Lake County are, in general, similar to those described for 

 Cook County, 



Control operations vrlll be aided by the relative accessi- 

 bility of all streairis. Installation and operation of devices will 

 be made difficult by rapid fluctuation in water levels in almost 

 all of the streams involved, 



A number of the streams examined in Lake County would 

 probably have been bypassed if the survey had taken place during 

 a period of dry weather. 



St. Louis Co\ inty t Contains 29 streams (Fig. 6), at least 6 of which 

 are unsuitiEle for sea lamprey spawning because of the presence of 

 barriers, steep gradients, industrial wastes, etc. 



Nineteen streams are considered to be marginal (Table $). 

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

 factors are likely to be vuifavorable enough to obstruct spawning 

 efforts. Several of these streams flow vmderground in the business 

 district of the City of Duluth. Barriers may be present in the 

 underground portions. The mouths of these streams are not located 

 easily. 



Nine of the streams examined flow into the St. Louis Ri- 

 ver. Twenty streams are located within the Duluth city limits. 



Four streams with productive potentials ranging from me- 

 dium to large are considered to be quite suitable for sea lampreys 

 despite the presence of partial barriers, irregular bottom, and the 

 possible limiting effects of low oxygen in the St, Louis River 

 (Footnote 2, Table 5), Three of these streams are medium sized, 

 averaging from 15 to 20 feet in width in the sections examined. The 

 remaining stream averages $0 feet in width. Electrical control de- 

 vices are recommended for these streams. Control in one stream will 

 be hindered by the presence of a reversing current, resulting from 

 lake seiches. 



26 



