IV-316 



Nearly one-quarter of present U.S. reserves are found on the continen- 

 tal shelf. Those reserves found under water depths of 200 feet or less 

 are of particular Importance to the estuarine zone; major areas identi- 

 fied as having significant crude oil deposits 1n near-shore water are 

 listed in Table IV. 4. 8. 



Sulphur mining 1s another major estuarine activity. Presently, most 

 of the sub-surface extraction is concentrated 1n three mines, two 

 located on the Continental Shelf several miles off the Louisiana coast, 

 and the third in a coastal bay off the same State. By 1970, these 

 three mines are projected to supply about 2.5 million tons of Frasch 

 sulphur, or about one-fourth of total projected domestic demand. 



Significant expansion of this industry 1n the estuarine zone seems un- 

 likely in the near future, since there are large and economically com- 

 petitive land-based sulphur sources in western Texas, as well as 

 competition from gypsum byproducts and from probable byDroduct recovery 

 under new air pollution restrictions. 



The mining of sand and gravel from the estuary floor does not compare 

 1n economic importance to the extraction and processing of petroleum 

 and sulphur. The present value of sand and gravel produced in coastal 

 bays and estuaries 1s estimated to be between 18 and 30 million dollars 

 a year. Marine shell deposits, particularly oyster shell, have been 

 harvested for years, mainly 1n the Gulf of Mexico and San Francisco 

 Bay. Production of shell was estimated to be about 21 million tons in 



