133 



Urban development tends to increase runoff, which, in turn, lowers the ground- 

 water table. Depending on the extent of development, this can cause a measurable 

 decrease in base flows during drought periods, which can have a significant effect 

 on salinity values in the tributaries. 



Growth in impervious areas increases both the magnitude and frequency of 

 flooding, which can have a decided effect on water quality in the estuarine en- 

 vironment. 



Rapidly expanding electi'ical power requirements and the resulting demand 

 for larger powerplants are requiring use of large volumes of estuarine water for 

 cooling purposes. One proposed plant on Chesapeake Bay will use about 1 million 

 gallons of water per minute for cooling, with a rise of 10 to 12 degrees Fahrenheit 

 in water temperatures. The exact effects of heat on many estuarine species is not 

 well known, but this problem is being studied by a number of scientific and edu- 

 cational institutions. 



The States of Maryland and Virginia have no technically reliable system to 

 evaluate the effect of thermal loads on specific Bay areas. On the other hand, some 

 public utility companies have spent considerable sums on the construction of 

 hydraulic models in an effort to estimate the effects of thennal electric plants 

 on aquatic environments. 



The protection of aquatic life from adverse water quality factors is much more 

 complicated in the estuary because of its diversity of life and the fragile nature 

 of its ecological interrelationships. The subtly shifting estuarine equilibrium can 

 easily move toward ecological disaster through neglect or mismanagement. A 

 grave example of our lack of understanding of ecological balance occurred in 

 Virginia in 1966, when the oyster crop was virtually destroyed by Michinia 

 nelsoni — ^MSX. A better knowledge of the basin system might have minimized 

 the spread of this oyster-killing fungus. 



Accelerated urban development, an increasing amount of leisure time, and a 

 generally expanding level of personal income have created a great demand for 

 water-based recreation in the Bay area. Conversely, and ironically, the industrial 

 and economic base of the pro.sperity that generated the demand also threatens to 

 destroy the existing recreation potential by its deleterious effect on the water 

 quality upon which water-based recreation depends. 



There are other significant threats to the Chesapeake Bay environment. These 

 include both inter- and intra-basin diversions of fresh water inflows. Current 

 examples are first, the deepening of the Cheseapeake and Delaware Canal, which 

 will increase the net amount of water flowing from the head of Chesapeake Bay 

 into Delaware Bay from about 900 cubic feet per second to about 3,000 cu^bic feet 

 per second ; and second, the Baltimore water supply tunnel, which taps the 

 Susquehanna Rivera above Conowingo Dam. Fresh water diversions can alter 

 the salinity regime of the headwaters of the Bay, affecting the spawning of many 

 species offish. 



Many estuarine areas have been subject to the gradual destruction of wetlands 

 through filling for urban development. The once productive San Francisco Bay 

 has been reduced by approximately one-third through land reclamation opera- 

 tions. Wetlands, now recognized as "powerful biological engines," produce many 

 of the organic nutrients so necessary for the maintenance of the estuarine eco- 

 logical system. The extensive, well-established Chesapeake Bay wetlands must be 

 protected, now, from shortsighted land-use patterns. 



The great size of Chesapeake Bay, its little understood physical, chemical, and 

 biological parameters, and the effect which rapidly increasing population and 

 urban-industrial development have on the estuary, make necessary for the preser- 

 vation of the rare body of water a specialized study. Realizing this, the Congress 

 directed, in section 312 of the River and Harbor Act of 1965, that a complete study 

 of Chesapeake Bay be made by the Corps of Engineers, and that, as a part of this 

 study, a hydraulic model of Chesapeake Bay be constructed in the State of 

 Maryland. 



The Corps of Engineers, with the advice and support of many Federal agencies, 

 the States concerned with Chesapeake Bay, and a number of educational insti- 

 tutions of outstanding competence in Bay-oriented research, has prepared pre- 

 liminary plans for this authorized study of Chesapeake Bay. 



These plans take cognizance of the extreme complexity and reaction potential 

 within the Bay to the man made environment, and well note that no single po- 

 litical or social entity can have the requisite personnel, equipment, and techni- 

 cal know-how to accomplish the many si)ecialized studies needed for such a com- 

 prehensive investigation. 



