site for intensive spawning of striped bass was created by building the sea-level canal, 

 but it may transport eggs and larvae into unfavorable water. Biota are generally 

 diverse and abundant. Later analysis has shown that longer periods of hydrographic 

 observations than those of this study are required for accurate estimation of the net 

 transport in this very dynamic pipeline between estuaries. The best present estimate 

 is that there is probably little long-term net transport despite massive short-term 

 movement in response to tides and meteorological events (Pritchard. 1980). 



Future modifications in freshwater flow are of serious concern. Demand for 

 consumptive loss from the principal tributaries for irrigation, consumptive 

 industrial uses, and modest export for water supply outside of the Chesapeake 

 watershed may reach 5,360 cfs in summer by 2020 (Robinson, 1980). In contrast, 

 the low flow of record, experienced in 1 966, was 4,720 cfs and the long-term average 

 for the driest month, September, is 28,400 cfs. The Baltimore District of the Corps of 

 Engineers has initiated extensive studies involving the Chesapeake Bay Hydraulic 

 Model and contracted biological analysis to estimate the changes in salinity that 

 might result from future losses and the effects on specific biota and on the uses of the 

 Bay system (Shea et al., 1980; Withers, 1979). At the time of writing, the effects have 

 been simulated in the huge model, the largest estuarine hydraulic model in the world, 

 but analysis has not been completed. 



Heat 



Heat, in the form of wasted energy from large power plants fired by fossil fuels or 

 nuclear energy, caused some of the most vociferous arguments in the Chesapeake 

 Bay region in the late 1960s and through the 1970s. They focused on the proposals to 

 construct nuclear facilities at Calvert Cliffs near Cove Point and at Douglas Point in 

 the center of the striped bass spawning areas of the Potomac River. Concern 

 centered on effects of heat on migratory aquatic species and on entrainment losses 

 from the combined impacts of mechanical, thermal, and chemical stresses. 



It is not appropriate to detail here the long and convoluted efforts to achieve 

 adequate environmental protection along with adequate supplies of electricity. 

 Several principal events and trends have emerged: 



• High temperatures have been precluded by general restriction of thermal rise 

 across condenser systems to 10° F. This has, however, required enormous 

 quantities of water — Calvert Cliffs requires an estimated 5,500 cfs of Bay water, 

 making it the fourth largest "tributary" of the Bay. 



• Large areas are warmed. Calvert Cliffs warms about 500 square miles of water 

 less than 10° F as heat moves through the water to the atmosphere. Against high 

 natural variation in termperature, any effects are difficult to identify and 

 evaluate. 



• More recent permits have required cooling towers rather than pass-through 

 cooling, precluding heating effects on the open system and reducing, but not 

 eliminating, aquatic losses. 



Maryland has had a Power Plant Siting Law since 1971, which provides a tax of 

 . 1-.3 mil per kw of production. The resultant fund of about $5 to $6 million per year 

 has been applied in a wide variety of research projects related to generating opera- 

 tions and their effects as well as in evaluation of proposed sites, monitoring, and 

 acquisition of potential sites for utilities. About 290 research and study reports have 

 been supported, most of which deal with estuarine questions. The Second Thermal 

 Workshop of the U.S. International Biological Program was held at the Chesapeake 

 Biological Laboratory of the University of Maryland and focused on research in the 

 Chesapeake Bay and other estuaries (Mihursky and Pearce, 1969). Twenty-nine 

 papers and workshop summaries were presented. It is not yet possible to determine 

 whether or not the management of generating plants has eliminated significant 

 injury to estuarine uses, but it is clearly based on a large and expanding body of 

 relevant knowledge. 



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