Texaco and Gulf Oil began operating in the Oriente region of Ecuador in 1964 as a consortium. Texaco operated the Lago Agrio oil field from 1972 to 1993 and the Ecuador state oil company continued to operate the same oil fields after Texaco left. In 1993, Texaco was found responsible for dumping billions of gallons of toxic waste and they spent $40m cleaning up the area during the 1990s. In 1998, the Ecuadorean government signed an agreement with Texaco accepting the clean-up as complete and absolving Texaco of any further responsibility. That same year, an Ecuadorean scientific team took water and soil samples after Texaco left and found petroleum hydrocarbons at unsafe levels in almost half. The clean up was called "a sham" by critics.