PROBLEMS FROM DEVELOPMENT 107 



wells — as much as 60 million gallons a day for industrial use 

 in the Lake Charles area, and the rest for irrigation of rice. 

 At Lake Charles the total withdrawal from wells was only 

 2 million gallons a day in 1935, chiefly for public use. In the 

 following 13 years the public demand increased to 6 million 

 gallons a day, but the big increase in demand resulted from 

 industrial developments that used 54 million gallons a day 

 in September 1949. 



The area of rice irrigation is a belt 20 to 50 miles wide 

 that includes the Lake Charles area and extends eastward 

 as much as 75 miles. About 600,000 acres of rice has been 

 planted in this area annually for the past 10 years. Forty per 

 cent of the total acreage, about 250,000 acres, is irrigated 

 by water pumped from wells; possibly as much as 70 per 

 cent is flooded by water originating as ground water, be- 

 cause part of the water pumped from wells is drained from 

 the fields into ditches, bayous, and rivers, from which it is 

 pumped to flood additional acreage. 



The aquifers tapped by the large wells in southwestern 

 Louisiana are considered to be alluvial fan deposits of fresh- 

 water origin. Most of these sediments are now below sea 

 level, and since their deposition they may well have been 

 covered for some time by the sea, permitting replacement 

 of the original fresh water by salt water. The lower 200 feet 

 of the aquifer, which in Acadia Parish is more than 900 

 feet thick, still contains salt water in some places. An impor- 

 tant element in the geologic history of the region was the 

 lowering of sea level by more than 400 feet during the most 

 recent glacial epoch. This enabled the aquifer, deeply 

 eroded by the Mississippi River and several coastal streams, 

 to be flushed of whatever salt water it contained down to 

 levels far below the present sea level. The aquifer now con- 

 tains fresh water as far as 20 miles offshore to depths of 

 about 1,000 feet, as shown by recent drilling of oil test wells. 



Half a century ago the water in this ground-water reser- 

 voir was under sufficient artesian pressure to produce flow- 

 ing wells throughout the rice-growing area and southward 



