O o 



1 "-i^ 



oi E 



AMJJ ASON 

 Month 



J FMAMJJASOND 

 Month 



c 



35 1962 



30 

 25 

 20 

 15 

 10. 



5. 







5 

 10 

 15 



D 



25^ 1973 



J FMAMJJASOND 

 Month 



J FMAMJ JASOND 

 Month 



Figure 3-43. Freshwater supply of Calcasieu Basin: (A) mean monthly freshwater discharge and salinity; (B) 

 mean monthly rainfall surplus; (C) monthly rainfall surplus for a dry year; and (D) monthly rainfall 

 surplus for a wet year. 



One device used to prevent salt intrusion is wet- 

 land impoundment. These impoundments can provide 

 excellent habitats for waterfowl and furbearers, but 

 they no longer function effectively as nursery grounds 

 forestuarine-dependent fish and shellfishes. 



Indications are that water is becoming a limiting 

 factor for further industrial and agricultural develop- 

 ment in the Calcasieu Basin. Large groundwater with- 

 drawals for agriculture and industry are depleting the 

 ground water reservoirs. Currently local groundwater 

 levels around Lake Charles are falling at the rate of 

 about 4 m/yr (13 ft/yr) in the 150 m (492 ft) sand 

 stratum and 3 m (10 ft) per year in the 60 m (197 ft) 



sand stratum (part 2.5). Salt intrusion into the 60 ni 

 sand stratum has caused many industries to suspend 

 pumping (Zack 1973). Continued withdrawals of sur- 

 face water during critical summer months may increase 

 saltwater intrusion in surface waters. However, the 

 aquifer is a large one and regional ground water sup- 

 plies are adequate for some time (Harder et al. 1967). 



Analysis of P loads indicates that present input 

 levels will result in excessive states of eutrophication. 

 Industrial discharges into the ship channel are known 

 to have reached the dangerous levels, particularly the 

 concentration of mercury. 



126 



