Since 1971, there have been no blowouts spilling more 

 than 200 barrels of oil (USDI , 1976d: III-6) . Twenty-one 

 blowouts have occurred since 1953 (Table 1.11). The two 

 worst blowouts occurred in 1970 when Shell and Chevron pro- 

 duction accidents spilled a total of 83,500 to 160,500 bar- 

 rels of oil. Another significant event took place during 

 Hurricane Hilda in 1964, which caused at least 11 blowouts 

 (although the volume of oil spilled is not known) . 



Other sources of oil pollution resulting from OCS operations 



include pipeline leaks and ruptures, waste water disposal, and 



7 

 platform explosions and fires. The two major causes of 



pipeline accidents are through anchor dragging and internal 

 corrosion (USDI, 1976d: III-6) . In 1967, a. pipeline was 

 ruptured by an anchor and spilled about 161,000 barrels of oil 

 (Kash et_al. , 1973: 287). Since 1967, there have been 26 

 reported pipeline breaks in the Gulf of Mexico of greater than 

 50 barrels each (spills of 50 barrels or less are not required 

 to be reported) spilling a total of approximately 202,588 

 barrels (USDI, 1976d: III-6) . The percentage of total oil 

 spilled by offshore facilities accounted for by pipeline leaks 

 and ruptures can be significant. While pipelines are consider- 

 ably safer than barges as a means of transporting offshore oil 

 to shore (virtually all offshore oil is transported by pipe- 

 line), in 1971, pipeline leaks and ruptures accounted for 



7 

 Gulf of Mexico OCS oil operations have accounted for 96.4% of 



total U.S. OCS oil operations. (See Table 1.3.) 



46 



