11-59 



Mining from the estuary floor causes alteration of the estuarine 

 shape and water circulation characteristics, with a secondary effect 

 being the turbidity Droblems 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 suspended 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 s treams and 

 runoff enterino the system. Tributary influent quality is generally 

 a good index of the type and intensity of land use surroundinq and 

 upstream from estuarine systems, and can be a major cause of ecological 

 stress within the svstem. The comolex interactions between fresh and 

 salt water may naqnify the effects of pollutants carried into the 

 tidal regime, resulting in quality anomalies completelv alien to 

 either fresh or oceanic environments. 



Extent of Pollution Effects 



Environmental damage from human activities manifests itself in 

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

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



