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deteriorated. The diversity of fishes in the outfall area decreased to 16, 

 as compared to a normal 60 found 2 miles away. The biomass of fish 

 was also reduced near the waste disposal area; 160 pounds per acre 

 during the sugarcane grinding season, compared to 600 pounds per 

 acre 2 miles away (IV-5-10). 



DREDGING AND FILLING OPERATIONS 



Lag Vina Madre 



One good example of water quality changes from dredging and 

 filling operations is South Bay of the Laguna Madre system in Texas 

 (Figure IV.5.30). The dredging and redredging of the Brownsville 

 ship channel resulted in almost complete enclosure of the South Bay 

 from Laguna Madre. Settlement of suspended sediment has caused a 

 60 percent reduction in depth in South Bay and has changed the bottom 

 characteristics from desirable vegetative habitat to soft mud. The 

 water circulation has been reduced and salinities have increased, and 

 composition of the biological community has been altered in terms of 

 number and density of species (IV-5-10) . 



UNDERSEAS MINING OPERATIONS 



Petroleum production in the estuarine areas of the Nation is now big 

 business. The pollution potential of this extraction industry is stagger- 

 ing to the imagination. The damage that could occur to fish, wildlife 

 recreational utilization, and shoreline structures from well blows and 

 broken pipelines is immense. The oil industry is well aware of this 

 hazard, and since 1955 there have been only eight such incidents. The 

 primary pollutional effects of these occurrences to date have been high 

 mortality of waterfowl in the area of the oil slick and nuisance con- 

 tamination as a result of oil washing onto shoreline areas. 



The 1956 blowout in Louisiana w^as accompanied by a rather severe 

 fire. The crude oil spill was out of control for approximately 2 weeks. 

 Ecological studies for 2 years after the spill did not demonstrate any 

 significant damage to the biological community in the spill area as con- 

 trasted to control areas outside the sphere of influence (IV-5-10) . 



The well publicized blowout in Santa Barbara is another example 

 of water quality impact from mining operations. As a result of this 

 accident, in January 1969, large numbers of waterfowl were killed by 

 contact with the oil and some prime recreational beaches were con- 

 taminated. The total extent of damages to the ecosystem have not been 

 assessed and will await the findings of extensive studies. 



HEATED EFFLUENTS 



As population centers develop in the estuarine zones of the country, 

 demand for electric power increases. This growing power demand is 

 usually met through the construction of either fossil -fueled or nuclear- 

 powered thermo-electric plants. Since these plants are only between 20 

 and 40 percent efficient in the conversion of thermal energy to elec- 

 tric energy, tremendous quantities of heat must be wasted to the 

 environment. There are many examples of water quality changes due 

 to thermal discharges. 



42-847 O — 70 19 



