| Business | Phone |
| Aquoneering 6143 Victoria Ln, Billings 59106 | (406) 655-4660 |
| Archambault Co 2976 Monad Rd, Billings 59102 | (406) 655-1560 |
| Spectrum Engineering 1413 4th Ave N, Billings 59101 | (406) 259-2412 |
| Rooney Engineering Inc 100 N 27th St # 220, Billings 59101 | (406) 896-1305 |
| Hdr Engineering Inc 2334 Lewis Ave, Billings 59102 | (406) 656-8100 |
| Jmc Engineering 19 N 28th St, Billings 59101 | (406) 294-7200 |