| Business | Phone |
| Associated Natural Gas Inc 1670 Broadway, Denver 80202 | (303) 595-0813 |
| Atmos Energy Colorado-Kansas 1301 Pennsylvania St, Denver 80203 | (303) 000-1111 |
| Reliant Energy Svc 1050 17th St # 1450, Denver 80265 | (303) 620-9999 |
| Piceance Natural Gas Inc 1580 Lincoln St # 970, Denver 80203 | (303) 832-6465 |
| Optigas 370 17th St # 2750, Denver 80202 | (720) 974-5300 |