LAKE EUTROPHICATION AND PRODUCTIVITY 



that has an adverse influence on fish 

 may signal a trend that could soon 

 have detrimental effects on other life 

 dependent on water, including hu- 

 mans. Restoration of the Great Lakes 

 for fish should also restore their value 

 for all other uses. 



The essential measures that must 

 be taken from the environmental 

 standpoint to restore the lakes that 

 have been severely damaged (Erie 

 and Ontario) and reverse deteriora- 

 tion of the others (Michigan, Huron, 

 and Superior) are clear. The attack 

 must be basin-wide, must be initiated 

 expeditiously, and pursued vigor- 

 ously. The plan must include: (a) 

 improvement of land uses within the 

 drainages that have direct or indirect 

 influences on the lakes and their 

 tributaries; (b) elimination of sources 

 of physical, chemical, or biological 

 pollution entering the lakes directly 

 or indirectly; and (c) restoration of 

 favorable and productive fish popula- 

 tions within the lakes. 



Restoration of Environmental Con- 

 ditions — Improvements within the 

 drainage basin of the Great Lakes 

 will require extensive restoration of 

 vegetation and forests that were de- 

 stroyed by wasteful land practices of 

 the past century. This will improve 

 the water quality and increase the 

 stability of the flow of tributaries 

 entering the lakes. Land-use prac- 

 tices, both urban and domestic, must 

 be modified and closely regulated 

 to prevent toxic substances (pesti- 

 cides and others) and fertilizers from 

 entering the runoff of the drainages. 

 (See Figure VIII— 15) No practice 

 should be allowed that would influ- 

 ence streams or rivers biologically, 

 physically, or chemically in such a 

 way that water conditions would be- 

 come less favorable than those that 

 might be expected from natural runoff. 



The most crucial problem of lake 

 restoration is the elimination of all 

 sources and kinds of pollution that 

 enter the lakes. Any treated effluents 

 or domestic and industrial wastes that 

 are permitted to enter the lakes must 

 be of equal or better quality than 



the waters in the lakes they enter. 

 Effluent from waste treatment that 

 cannot meet these standards should, 

 after being treated to the highest 

 degree possible, be diverted into 

 drainages outside the Great Lakes 

 basin. These effluents would be of 

 higher quality than the water of 

 rivers into which they would be 

 diverted; thus, the practice of divert- 

 ing them from the Great Lakes would 

 have the dual benefit of preventing 

 degradation of the Great Lakes and 

 improving the water flow and quality 

 in rivers of the north and central 

 United States. 



Costs of water treatment (partic- 

 ularly for industrial wastes) might be 

 reduced greatly by the construction 



of inland waterways wherever feas- 

 ible to permit reuse of water and 

 provide channels for the diversion 

 of treated waste waters from the 

 Great Lakes basin. A number of 

 proposals for the construction of 

 such channels in the Great Lakes and 

 central U.S. regions have already 

 been made. It may, in fact, be neces- 

 sary to divert excess water from the 

 Great Lakes region to irrigate the 

 arid south-central sections of the 

 United States before the end of this 

 decade. Present collective drainage- 

 disposal systems are a move in this 

 direction; but, unfortunately, they 

 are not being planned to fit a basin- 

 wide system and will probably have 

 to be modified or rebuilt at great 

 cost before the century ends. 



Figure VIII— 15 — THE EFFECT OF FERTILIZER ON 

 NITRATE CONCENTRATIONS IN RIVERS 



U.S. HEALTH 

 LIMIT 



J J 



Months 



The graph shows the difference in nitrate concentrations between two rivers in 

 Illinois — the Kaskaskia River, which drains a heavily fertilized farming area, and 

 the Skillet Fork River, which drains an area where little fertilizer is applied. The 

 threefold increase in nitrate concentration for the Kaskaskia River between 

 1945-1950 and 1956-1968 follows the increased use of industrially fixed nitrogen 

 fertilizers. 



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