OF LAKES 



perature, with deleterious effects on 

 efficiency. Immediate and systematic 

 work is required on the climatology 

 of coastal currents at various loca- 

 tions and in various seasons. Also, 

 it is necessary to conduct a long 

 series of large-scale diffusion experi- 

 ments to define the likely "influence 

 zones" of potential effluent outlets, 



again as a function of location around 

 lakes, particularly the Great Lakes. 



Given the present dearth of knowl- 

 edge, it would take perhaps ten years 

 of concentrated effort to achieve some 

 sort of consensus on the most urgent 

 topics (climatology of currents and 

 influence zones) that affect the most 



important of our lakes, the Grea' 

 Lakes. It may take 25 years to build 

 up a solid enough base of funda- 

 mental knowledge (dynamics of cur- 

 rents, mass transport, internal waves, 

 turbulence, and mixing) for the con- 

 struction of more detailed prediction 

 models for long-term planning and 

 "resource management." 



The Effects of Thermal Input on Lake Michigan 



Our concern for the environmental 

 quality of the Great Lakes arises from 

 their relatively closed condition. The 

 lakes serve as channels for internal 

 navigation, as highways to the 

 world's oceans, as sources of water 

 for cities and industries, including 

 electric power, as recreational re- 

 sources — and as sinks for the water- 

 borne wastes from urban and agri- 

 cultural land. As the multiple uses 

 increase, problems appear. In spite 

 of its large volume and generally 

 good water quality, some parts of 

 Lake Michigan — for example, south- 

 ern Green Bay and some harbors 

 near Chicago — are becoming grossly 

 polluted; this is a development that 

 the public is not prepared to tolerate 

 any longer. The threat to environ- 

 mental quality is a direct consequence 

 of the multiple uses to which the 

 lakes are put and of the rapid rise 

 of population over the last century, 

 particularly in the southern half of 

 the region. 



With present agricultural practice 

 and systems of waste disposal, the 

 Great Lakes — whether we like it or 

 not — are the receptacles of waste 

 products of all kinds, some of them 

 long-lived. They are becoming over- 

 loaded beyond their natural capacity, 

 in some places intolerably so. Is this 

 an inevitable consequence of a large, 

 highly industrialized civilization with 

 a high standard of living? It need not 

 be so, if we are willing to pay the 

 price in regulatory planning and in 

 dollars to maintain reasonable stand- 



ards of water quality and to work 

 with nature rather than against it. 

 It should be noted that water quality 

 remains high in the northern part of 

 Lake Michigan and in Lake Superior. 

 This represents a national treasure 

 that must be conserved and wisely 

 managed for posterity. 



Heat Dissipation Projected 

 to 1990 



One form of waste is waste heat. 

 This particular use of Lake Michi- 

 gan's waters is expected to grow 

 rapidly with growing power demands 

 by industry and by home-owners and 

 institutions seeking to improve their 

 interior environments (e.g., through 

 airconditioning). The question is 

 whether the price we pay for this 

 must include biological deterioration 

 of the lake. 



It is perhaps not generally realized 

 that some of the largest generating 

 plants in the country already use Lake 

 Michigan for cooling. The 1970 col- 

 umn in Figure VIII— 13 indicates that 

 the equivalent of 16,000 megawatts 

 is added to the lake in the form of 

 heat at present. According to a fore- 

 cast by the Argonne National Labo- 

 ratory, this figure is expected to be 

 nearly doubled by 1975, when further 

 large units (many of them nuclear 

 generating stations) now under con- 

 struction or being planned come into 

 operation. Beyond that, projections 

 of the increase are largely guesswork, 



but must presumably bear some re- 

 lation to the projected rise in national 

 demand, forecast as doubling every 

 ten years up to 1990. If this demand 

 is to be met, it will be done with 

 larger units, mainly nuclear, and 

 these need large heat sinks to operate 

 at maximum efficiency. There are 

 only three heat sinks with sufficient 

 capacity: the ocean, the atmosphere, 

 or (for the Midwest) the Great Lakes. 

 The interest of power companies in 

 Lake Michigan is, therefore, not sur- 

 prising. 



Effect on the Lake 



Even allowing for improvements in 

 thermal efficiency, heat dissipations 

 from Lake Michigan for 1970, 1980, 

 and 1990 are likely to increase at a 

 rate that slightly more than doubles 

 every ten years. (See Figure VIII-13) 

 If these estimates are accepted as rea- 

 sonable, we may calculate the orders 

 of magnitude of the effect on the 

 lake. This has been done in three 

 ways in Figure VIII-13. A typical 

 daily total of heat input from the sun 

 in early summer is 300 of the units 

 used in the figures (gram-calories per 

 square centimeter of lake surface). 

 The daily total heat output from 

 power stations in 1990 is less than 

 one percent of this, if spread over 

 the whole lake surface. But this is, 

 of course, unrealistic, bearing in 

 mind that all the heat is injected near 

 shore. 



257 



