| Southern States Cooperative Inc | Owner/operator | | | 1 |
| Southern Stear Central Gas Pipeline, Inc. | Owner/operator | Owensboro, KY | | 1 |
| Southern Transmission Company | Owner/operator | | | |
| Southern Union Gas Co | Owner/operator | | | |
| Southern Union Gas Services, LTD | Owner/operator | Fort Worth, TX | | 15 |
| Southern Union Intrastate Gas Pipeline | Owner/operator | Fort Worth, TX | | 1 |
| Southwest Gas | Owner/operator | Las Vegas, NV | 1 | 1 |
| Southwest Gas Storage Company | Owner/operator | | 3 | 4 |
| Southwest Gas Systems, Inc. | Owner/operator | | | 1 |
| Southwest Gas Transmission Company | Owner/operator | | | |
| Southwest Gas Transmission Company, A Limited Partnership | Owner/operator | Las Vegas, NV | | 1 |
| Southwest Iowa Renewable Energy, LLC | Owner/operator | Council Bluffs, IA | | 1 |
| Southwestern Energy Prod. Co | Owner/operator | | | |
| Southwestern Energy Production Company | Owner/operator | | | |
| Southwestern Gas Pipeline Inc | Owner/operator | Oklahoma City, OK | | 1 |
| Southwestern Public Service Co | Owner/operator | Denver, CO | | 5 |
| Southwestern Virginia Gas Co | Owner/operator | Martinsville, VA | | 1 |
| Southwinds Inspection | Third-party inspection | | 1 | |
| Sovde Enterprises, Inc. | Contractor | | 1 | |
| Sowega Power LLC & Baconton Power LLC | Owner/operator | Baconton, GA | | 1 |
| Spectra Energy | Owner/operator | | 4 | |
| Spectra Energy Corp/NextEra Energy/Duke Energy | Owner/operator | | 2 | |
| Spectra Energy Early Grove Company | Owner/operator | | | |
| Spectra Energy Transmission LLC | Owner/operator | | 1 | |
| Spectra Energy Virginia Pipeline Company | Owner/operator | | | |
| Spectrum Field Services Inc | Owner/operator | | | |
| Spelman Pipeline Holdings LLC | Owner/operator | Mentor, OH | | 1 |
| Spindletop Gas Storage Facility | Owner/operator | | | |
| Spinnaker Exploration Company, L.l.c. | Owner/operator | | | 1 |
| Spire Alabama Inc. | Owner/operator | Birmingham, AL | | 1 |
| Spire Gulf Inc. | Owner/operator | Mobile, AL | | 1 |
| Spire Inc | Owner/operator | | | 1 |
| Spire Missouri Inc. East | Owner/operator | Saint Louis, MO | | 2 |
| Spire Missouri Inc. West | Owner/operator | Saint Louis, MO | | 1 |
| Spire MoGas Pipeline LLC | Owner/operator | Houston, TX | 1 | 1 |
| Spire Moga's Pipeline LLC | Owner/operator | | 1 | |
| Spire STL Pipeline LLC | Owner/operator | Saint Louis, MO | 1 | 1 |
| Spire Storage Salt Plains LLC | Owner/operator | Houston, TX | | 1 |
| Spire Storage West LLC | Owner/operator | Houston, TX | 3 | 3 |
| Sponte Operating, Inc. | Owner/operator | Dallas, TX | | 7 |
| Sport Pipeline Corp | Owner/operator | | | |
| Sprague Operating Resources LLC | Owner/operator | | | 15 |
| Sprague Operating Resrcs LLC | Owner/operator | | | 3 |
| Spring Ridge Constructors LLC | Contractor | | 1 | |
| Springfield Mo Municipal Gas | Owner/operator | Springfield, MO | | 1 |
| Springfield Pipeline LLC | Owner/operator | | | 22 |
| Springfield Terminal Inc | Owner/operator | | | 2 |
| Springfield, City Utilities Of | Owner/operator | Springfield, MO | | 1 |
| Springfield, Mo Muncipal Gas | Owner/operator | | | |
| Sprint Pipeline Services, L.P. | Contractor | Pearland, TX | 1 | |