Cladophora downstream. Major water withdrawals without flow stabili- 

 zation would probably decrease production of this alga. With evi- 

 dence of naturally high background nutrient levels in the upper river, 

 it is speculated that Cladophora would continue to play a major role 

 in the Yellowstone, even following the abatement of cultural enrich- 

 ment. 



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