IV-399 



California and Alaska. Isolated areas of the other types of mining 

 activity also are shown in the table. The economics of bottom 

 mining and of water extraction compared to the availability of ma- 

 terials from other sources seems to preclude extensive development, 

 except for materials such as sand and gravel. 



FRESH WATER INFLOWS 



The quality of estuarine areas is dependent not only on direct 

 waste sources but also on the quality of the streams and runoff 

 entering the system. Tributary influent quality is generally a 

 good index of the type and intensity of land use in the surround- 

 ing area and upstream from an estuarine system, and it 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. 

 It is, therefore, imperative to examine the secondary or relatively 

 uncontrollable pollutant source of tributary inflow. 



The first item to be considered is the quality of major rivers 

 and streams entering the estuarine area. Many streams are sub- 

 jected to various uses and abuses in their upstream reaches; by 

 the time they reach the coastal area the full cumulative effects 

 of pollution are exerted. If no regulatory actions were taken, 



