In 1993, as recommended by the Council on Regulatory Needs, the guidelines were reviewed and updated. The Council was reconvened under the leadership of Governor Mike Sullivan of Wyoming and Governor John Engler of Michigan. A Guidelines Review Committee was formed to consider which portions of the original guidelines needed to be updated or revised.
In early 1993, the Council established five committees to address the program areas identified by the committee as well as expansion of the guidelines to include Naturally Occurring Radioactive Material (NORM) and abandoned wells. Draft committee reports were discussed, compiled and edited to develop a revised guidelines document. The revised guidelines were presented to IOGCC by the Council in December 1993 and adopted by IOGCC in March 1994.
The revised guidelines were published as "IOGCC Environmental Guidelines for State Oil & Gas Regulatory Programs." The questionnaire was revised to reflect the updated guidelines.
Also, in March 1993, EPA issued a notice clarifying the status of certain associated wastes. EPA clarified that waste from crude oil reclamation, crude oil pipelines, gas plants and feeder pipelines were included in the E&P exemption. This formalized and clarified existing practice.
In 1994, New Mexico, Louisiana and New York were reviewed. Since these reviews were begun before the revised guidelines and questionnaire were available, the original guidelines were used.
In 1995, Ohio and Kentucky were reviewed using the revised guidelines. Colorado and Illinois were reviewed in 1996. In 1997, North Dakota was reviewed.