336 



of the powerplants were in the coastal zone ; it is anticipated that over 

 30 percent of the plants will be located there in the late 1970's. 



Estuarine areas are also very important highways of commerce, and 

 thousands of commercial vessels (foreign and domestic, from ocean 

 liners to barges, traverse the coastal waterways each year. Added to 

 this are many of the 1,500 Federal vessels and many, nearly 8 million, 

 recreational vessels. All of these watercraft carry people and/or cargo, 

 and are a real or potential pollution source. 



Mining from the estuary floor causes alteration of the estuarine 

 shape and water-circulation characteristics, with a secondary effect 

 being the turbidity problems associated with material removal. Mining 

 of sand and gravel from the estuarine floor are universal while oyster 

 shell dredging in any great quantity is restricted to the Gulf coast. 

 These operations remove part of the estuarine floor with a concomitant 

 destruction of habitat and life. There are also great amounts of sus- 

 pended and settleable solids frequently released into the water, from 

 which they are redeposited in other places. 



The water quality of estuarine areas is dependent not only on direct 

 waste sources but also on the quality of the inflowing streams and run- 

 off entering the system. Tributary influent quality is generally a good 

 index of the type and intensity of land-use surroundings and up- 

 stream from estuarine system and can be a major cause of ecological 

 stress within the system. The complex interactions between fresh and 

 salt water may magnify the effects of pollutants carried into the tidal 

 regime, resulting in quality anomalies completely alien to either fresh 

 or oceanic environments. 



EXTENT or POLLUTION EFFECTS 



Environmental damage from human activities manifests itself in 

 changes in water quality and in changes in the living communities. 

 Either or both may be caused by any of the kinds of pollution or 

 sources of pollution mentioned earlier. One key to the degree of en- 

 vironmental impact is measurement of alteration in water quality. 

 Extensive data have been collected on a few of the estuaries with 

 the most severe problems, and limited information is available on 

 other estuarine systems to outline the emergence, or document the 

 existence, of water-quality problems. 



Examples of estuarine systems that show definite documented water- 

 quality degradation as a result of human activities are these : Penob- 

 scot Bay, Boston Harbor, Moriches Bay, New York Harbor, Raritan 

 Bay, Delaware estuary, Baltimore Harbor, Potomac River, James 

 River, Charleston Harbor, Savannah River, Biscaj^ne Bay, San Juan 

 Harbor (P.R.) , Tampa Bay, Pensacola Bay, Mississippi River, Galves- 

 ton Bay, Laguna Madre, San Diego Bay, Santa Monica Bay, San 

 Francisco Bay, Columbia River, Puget Sound, Silver Bay (Alaska), 

 and Hilo Harbor (Hawaii) . 



Pollutional damage to estuarine ecosystems may be sudden and dra- 

 matic as fish or other equatic life forms suddenly dying, or it may be 

 so gradual as not to be noticed for many years. Many studies of differ- 

 ent aspects of estuarine biology have been made, but there are only a 

 few cases in which comprehensive ecological studies have been made 

 of pollutional effects. 



