categories. A point source is a loca- 

 tion at which nutrients are released in 

 quantity and concentration compatible 

 with practical means of nutrient re- 

 moval. A diffuse source is an area from 

 which nutrients are released in a manner 

 not compatible with practical means of 

 nutrient removal. Municipal sewage 

 effluent and industrial wastes are point 

 sources, while urban-storm and agricul- 

 tural runoff are diffuse sources. These 

 are important concepts for management 

 purposes because excess effort to reduce 

 point discharges may have little effect 

 on water quality in areas with high 

 nonpoint discharges (Uttormark et al. 

 1974). The specific nutrient contribu- 

 tors in municipal sewage are primarily 

 human waste and detergents. In agri- 

 cultural runoff, chemical fertilizers, 

 animal excrement, and soil nutrients are 

 the principal sources. 



In conclusion, it can be said in 

 general that eutrophication in the MDPR 

 is caused by two problems. First, more 

 waste water is being generated from 

 agriculture, domestic wastes, urban 

 runoff and industry. Second, these 

 waters are flowing directly to water 

 bodies via canals that bypass the normal 

 overland flow through wetlands. 



TOXINS 



The introduction of toxic materials 

 (pesticides, herbicides, heavy metals, 

 PCB's, etc.) into the MDPR has become an 

 increasingly serious problem. The prob- 

 ability of toxic pollution is great 

 because of the density of, petrochemical 

 industries, large urban centers, and 

 agricultural areas adjacent to wetland 

 estuarine ecosystems. The MDPR receives 

 toxic input from industrial plants, 

 hazardous waste sites, and illegal 

 dumping grounds; pesticides from agri- 

 cultural runoff; pesticides and heavy 

 metals from urban runoff; petroleum 

 hydrocarbons from oil exploration; and 

 herbicides for aquatic weed control. 



The petrochemical industries pro- 

 duce a variety of products such as vinyl 

 chloride, nitric acid, hydrochloric 



acid, methyl-ethyl ketone, styrene, 

 sulfuric acid, acrylonitrile, benzene, 

 and a variety of herbicides and pesti- 

 cides (Mumphrey et al. 1978). All 

 manufacturing processes produce waste 

 byproducts. In the past, chemical 

 wastes have often been disposed of in 

 the cheapest possible manner without 

 regard for environmental consequences. 

 In many cases, the wastes have leaked 

 into the environment (Dow and Garcia 

 1980). The Barataria basin has 27 

 potential hazardous waste sites that 

 have been identified and an unknown 

 number of illegal dumping sites (USEPA 

 1980). 



Although data on toxic substances 

 are scant, they indicate severe prob- 

 lems, possibly a result of hazardous 

 waste dumping. Barataria Bay was char- 

 acterized by the EPA as having chronic 

 contamination of PCB's (polychlorinated 

 byphenyls) , whose source was unknown 

 (Cumiford 1977). 



Excessive pesticide concentrations 

 that violate the EPA criteria for 

 aquatic life and the USACE no-discharge 

 criteria were recorded in Little Lake- 

 Barataria Bay, the Gulf Intracoastal 

 Waterway below Algiers, Bayou Lafourche, 

 Lakes Cataouatche and Salvador, and Lac 

 des Allemands. Bayou Lafourche had pes- 

 ticide violations for aldrin, parathion, 

 2,4-D, silvex, and lindane; Lake 

 Cataouatche, Lake Salvador, and Lac des 

 Allemands for 2,4-D, silvex, and lin- 

 dane. These pesticides are used in the 

 production of agricultural products and 

 aquatic weed control. The improper 

 disposal of unused pesticides and pes- 

 ticide containers, agricultural runoff, 

 and direct entry via application are 

 probable routes for these pesticides 

 into the receiving water bodies (USACE 

 1980). 



Pesticide residues have had an ef- 

 fect on aquatic organisms and bird popu- 

 lations. The brown pelican (Pelecanus 

 occidentalis) population in Louisiana 

 was reduced from 50,000 in 1933 to ex- 

 tirpation in the early 1960's probably 

 because of decreased reproductive capa- 

 bilities due to pesticide residues (DDE, 

 dieldrin, and endrin) in adult birds and 

 their eggs (Blus et al. 1979). Approxi- 



157 



