mately 800 birds were reintroduced dur- 

 ing the period from 1968-1976 into the 

 lower Barataria basin. Another die-off 

 occurred in 1975, coinciding with unusu- 

 ally high endrin residues in the Bara- 

 taria Bay that spring. High endrin 

 residues were found in the pelican eggs 

 (Blus et al. 1979). The last natural 

 nesting colony of pelicans in the MDPR 

 (before restocking was initiated) was on 

 North Islands (Chandeleurs) (J. A. 

 Valentine, USFWS retired, Lafayette La., 

 pers . comm.) . 



Millions of fish, mostly menhaden, 

 died in the Mississippi Delta area in 

 the early 1960's of endrin poisoning 

 that was traced to a company in Memphis, 

 Tennessee that poured wastes into the 

 Mississippi River. (J. A. Valentine, 

 USFWS retired, Lafayette, La., pers. 

 comm.). Except for these dramatic exam- 

 ples of pesticide-related fish and 

 wildlife mortality, little data are 

 available on the impact of chronic toxic 

 input on MDPR biota. 



Toxic pollution of air, water, and 

 food has a long term cost in terms of 

 human health. South Louisiana shows an 

 increased rate of certain types of can- 

 cers, compared with the national 

 average. Higher rates of cancer mor- 

 tality have been statistically linked to 

 drinking water from the Mississippi 

 River, with its variety of chemical 

 carcinogens, and to residence in 

 counties where the petroleum industry is 

 most heavily concentrated (Hoover et al. 

 1975; Page et al. 1976, Blot et al. 

 1977). A relationship between respira- 

 tory cancer and proximity of residence 

 to wetlands in Louisiana has also been 

 demonstrated (Voors et al. 1978). 



SALT WATER INTRUSION 



Salt water intrusion is a major 

 problem in the MDPR. It leads to the 

 death of wetland vegetation, especially 

 fresh and intermediate types (Craig and 

 Day 1977), and increases the rate of 

 wetland loss (Craig et al. 1979). It 

 also threatens municipal water supplies. 



Salt water intrusion occurs natu- 

 rally during the abandonment stage of 

 the deltaic cycle, but human activity 

 has accelerated the process. The most 

 important factor causing intrusion is 

 the construction of canals that increase 

 water exchange. Major navigation canals 

 connecting coastal and inland areas are 

 primary factors, but any canal that 

 establishes a new hydrologic connection 

 contributes to salt water intrusion. 

 Intrusion has been demonstrated for the 

 Calcasieu basin (Gosselink et al. 1979), 

 the Terrebonne and Barataria basins 

 (Craig and Day 1977; Hopkinson and Day 

 1979; Van Sickle et al. 1976), and the 

 Pontchartrain basin (Gagliano et al . 

 1973). 



Van Sickle et al. (1976) reported 

 an average rate of salinity increase of 

 0.009 ppt per month at St. Mary's point. 

 Little Lake, a fresh water body early in 

 this century, has changed to an estuary 

 with a mean salinity of about 8 ppt. 

 This change has induced a landward shift 

 of brackish and saline marshes (O'Neil 

 1949; Chabreck 1972; Chabreck and 

 Linscombe 1978) with a concomitant 

 increase in wetland loss (Craig et al. 

 1979). 



Under natural conditions, water 

 exchange between the lower and upper 

 parts of the Barataria basin occurred 

 slowly through many shallow bayous and 

 lakes and by overland flow. Saline water 

 at the seaward end of Barataria basin 

 formerly reached Lake Salvador only via 

 a circuitous route through Barataria Bay 

 via Grand Bayou or Bayou Dupres to 

 Little Lake via La Bayou Perot or Bayou 

 Rigolette and Barataria to Lake Salvador. 

 Much of this route was shallow and in- 

 direct, and tended to prevent rapid 

 water exchange. 



Now, an array of straight, deep 

 canals such as Barataria Basin Waterway, 

 Turtle Island Cutoff, and Bayou de 

 Families Waterway have made new hydro- 

 logic connections within the basin. In 

 the southwestern part of the basin, a 

 series of petroleum and navigation 

 canals have created new connections 



158 



