V-267 



"Large cities, especially Baltimore, Washington and 

 Norfolk, arose because of the Bay and increasingly impinge 

 upon it. This is the southern end of the eastern megalopo- 

 lis, with an enormous growth of population in sight. 



"Salinity is near zero at the head of each tributary and at 

 the north end of the Bay and about 30-31 parts per thousand 

 at the Capes. Circulation is controlled primarily by river 

 flow and the resulting density gradients. A strongly two- 

 layered stratified system develops in summer, with a some- 

 what weaker winter system, and general vertical mixing 

 occurs in spring and fall. This produces a net downstream 

 flow of surface water and net upstream flow of deeper waters. 

 This pattern of circulation affects many of the organisms 

 of the Bay. 



USES 



"Transportation 



"Ships have used the Bay since its discovery in the 16th 

 century, and Baltimore and Norfolk are amonq the Nation's 

 great ports. In 1964, 107,253,730 tons of material were 

 handled by these norts, and Baltimore alone receives about 

 5,000 ocean-going ships per year. This commercial activity 

 affects other uses of the Bay, principally through pollution 

 by bilge-pumping and accidental spillage and through insati- 

 able demands for the deepening and maintenance of channels. 



