|Fig. 1: Ixtoc I oil well releasing thousands of metric tons of oil into the gulf. (Source: Wikipedia Commons).|
On June 3, 1979, an exploratory well named Ixtoc I in the Bay of Campeche in the Gulf of Mexico leaked.  The spill had major impact because the Gulf of Mexico is an extremely important, both as a diverse ecosystem and as area rich in energy resources.  Fossil Fuels were originally discovered in the Gulf of Mexico in the 1970s. This led to an expansion of oil wells in the Campeche Sound.  The spilling well was eventually capped 290 days later on March 23, 1980, after much damage had been done to the surrounding areas in Mexico and Texas.  The Ixtoc I oil spill became the largest oil spill to date. It surpassed the Amoco Cadiz oil spill that leaked 68 million gallons of oil off the coast of Brittany, France in 1978. [3,4]
Petroleos Mexicanos (PEMEX) drilled the Ixtoc I at the longitude 90°13'W and the latitude 19°24'N on December 10, 1978.  The exploratory well was 80 kilometers northwest of the city Ciudad de Carmen which lies on the Bay of Campeche in Mexico.  The well was drilled at a depth of 3,600 meters with the water depth at the area only being 50 meters. 
In the early hours of June 2, 1979, the Ixtoc well started to lose drilling mud, and circulation was lost in the well.  There were attempts to regain circulation in the well, but they were not successful.  Then at about 3:30 AM, the well exploded, caught fire, and destroyed the platform, causing gas and oil to leak from the sight.  The drilling of two relief wells was decided on by PEMEX as a solution to stop the spread of oil. Unfortunately, those two wells did very little to stop the spread. 
During the 290 days that the well remained uncapped, 475,000 metric tonnes of oil (3.4 million barrels) leaked into the Gulf of Mexico. [1,2] (See Fig. 1.) 72% of the spilled oil evaporated or sank to the sea floor, 6% washed ashore, 3% drifted to the beaches in the U.S., 12% biodegraded, and about 7% was burned or recovered from the site. 
The density of the oil was 0.84 g/cm3, it was 50% saturated and it had 10.5 ppm and 55 ppm of Nickel and Vanadium respectively. 
The United States was given 2 months to prepare for the oil slick from the Bay of Campeche and arranged a plan to protect the Texas coast.  Oil from the Ixtoc I reached American waters on August 6, 1979.  The beaches and ecosystem of the Texas coast were harmed at that time not only by the Ixtoc I leak but also the sinking of the Burmah Agate oil tanker on November 6, 1979. 
It took the Mexican government 4 months to organize a group to analyze the damage done by the spill. Even then the lack of knowledge of the conditions pre-spill made it difficult to quantify the damage done.  The Mexican government eventually found that the oil spill killed many species of shrimp and polluted sandy beaches, mangroves, coastal lagoons, and rivers. 
The Ixtoc I oil spill was the largest oil spill to date. However, lack of information about the oil spill made it difficult to assess the damage done.  The spill stimulated many scientists to begin studying the surrounding area of oil wells in order to be able to quantify damage if a disaster were to occur.  In 2010, the largest oil spill to date also happened in the Gulf of Mexico with the Deepwater Horizon leak releasing 4.9 million barrels of oil in the northern Gulf of Mexico. 
The Ixtoc oil spill of 1979 fundmentally changed the way we look at oil spills.
© Henri Fernandez. The author warrants that the work is the author's own and that Stanford University provided no input other than typesetting and referencing guidelines. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
 A. Jernelöv and O. Lindén. "Ixtoc I: A Case Study Of The World's Largest Oil Spill," Ambio 10, 299 (1981).
 L. A. Soto et al., "The Environmental Legacy of the Ixtoc-I Oil Spill in Campeche Sound, Southwestern Gulf of Mexico," Front. Mar. Sci. 1, 57 (2014).
 L. Garmon, "Autopsy of an Oil Spill," Science News 118, 267 (1980).
 C. E. Restrepo et al., "Ixtoc I Oil Spill Economic Impact Study," Restrepo and Associates, 1982.