exerted overall beneficial effects 

 on oysters. Although oyster mortali- 

 ties occurred in the immediate area 

 affected by flooding, increased pro- 

 duction occurred in areas further re- 

 moved due to nutrients introduced by 

 river water and elimination of oyster 

 predators by reduced salinity. Dugas 

 (1977) reported that increased fresh- 

 water inflow in Hydrologic Unit II of 

 coastal Louisiana during 1973, 1974 

 and 1975 was responsible for in- 

 creased oyster production. 



WILDLIFE RESOURCES 



Freshwater introduction would 

 benefit wildlife resources as well. 

 Productivity of wildlife resources 

 in any area is directly dependent 

 upon habitat quality of the area. 

 Generally speaking, wooded swamps 

 and fresh-intermediate marshes are 

 significantly more productive than 

 salt marsh for the majority of wild- 

 life species of commercial and rec- 

 reational importance. Data demon- 

 strating the value of the various 

 marsh types for commercial fur har- 

 vest and sport hunting potential are 

 given in Table 1. Introduction of 

 fresh water from the Mississippi Riv- 

 er will preserve and restore wooded 

 swamps and fresh-intermediate marsh- 

 es by reducing salinity levels. In 

 addition, production of vegetation 

 will be enhanced by nutrient-rich 

 river water. The fact that Missis- 

 sippi River water contains a higher 

 level of nutrients than adjacent 

 estuaries has been documented by 

 Ho and Barrett (1975). 



ADVERSE IMPACTS 

 FISHERY RESOURCES 



fishery-related problems due to 

 freshwater diversion in Louisiana 

 are poor water quality and rela- 

 tively lower water temperatures in 

 the Mississippi River as compared 

 to the adjacent estuaries. 



The Mississippi River receives 

 industrial wastes, runoff from 

 agricultural lands and municipal 

 sewage from numerous sites located 

 upstream from and within the study 

 area. As a result, water quality in 

 the river is generally poor, and 

 levels of various pollutants in the 

 river are significantly higher than 

 those found in the areas which would 

 receive diverted river water. Table 

 2 is a comparison of levels of 

 selected parameters in the river and 

 various receiving bodies in the 

 MLEA study area. Fecal coliform 

 levels are high in the river. High- 

 est concentrations occur downstream 

 from Baton Rouge and New Orleans at 

 Plaquemine and Violet, Louisiana, 

 respectively, where average concen- 

 trations of fecal coliform bacteria 

 are 1,000 and 3,100 colonies per 100 

 milliliters (Wells 1980). Discharge 

 of river waters through existing 

 structures has historically led to 

 closure of oyster grounds by public 

 health officials. However, in- 

 creased production of oysters due to 

 well planned introduction of fresh 

 water should outweigh effects of 

 lost harvest due to occasional clos- 

 ing of fishing grounds. Heavy met- 

 als, phenols, pesticides and poly- 

 chlorinated biphenyls are also often 

 present at unacceptable levels in 

 the river. However, it is conceiv- 

 able that pollution problems due to 

 industrial waste and municipal sew- 

 age will be lessened in the future 

 due to improved treatment facili- 

 ties . 



Impacts of freshwater introduc- 

 tion upon fishery resources would 

 not be entirely beneficial. Major 



Mississippi River waters are 

 generally about 5°C colder than adja- 

 cent estuarine waters during the 



380 



