Consistent with the consolidation of the City and Parish governments in 1984, the Utilities System undertook management and operation on the natural gas distribution system owned by the Terrebonne Parish Police Jury (Parish System) around 1985 and consolidated it with management and operations of the City's municipal system. In the fall of 1994 the systems were merged, in that the income and obligations of the Parish System were assumed by the city under a local services agreement (Ordinance Number 5328 adopted October 12, 1994) and a uniform rate was enacted (Ordinance Number 5330 adopted October 26, 1994).

On May 22, 1996, with the adoption of Terrebonne Parish Ordinance Number 5600, under provisions of Act 18 of the 1995 Louisiana Legislature, the physical assets of the Parish System were conveyed to the City. The merger was accomplished smoothly. Because of differences in physical and operational characteristics of the systems they remain hydraulically separate and will likely remain so for the foreseeable future. The department continues to monitor some operational aspects of the systems independently and continues to use the name conventions of "Urban System" for the former City or municipal system and "Parish System" for the former Police Jury System.

The service area of the Urban System generally covers the City Limits and certain immediately adjacent developed areas. The Parish System primarily services three bayou arteries south, west and northwest of the City.

The municipal gas system originated with a distribution system that was acquired by the City from a private Owner in about 1939. By December 31, 1999, 14,142 customers were being served by a distribution system which consists of approximately 378 total miles of mains servicing approximately 72.5 square miles.