| Business | Phone |
| Belt Engineering 22049 Yerba Santa Rd, Sonora 95370 | (209) 533-0847 |
| L R Davey 6 S Washington St # 16, Sonora 95370 | (209) 532-5471 |
| Ewr Engineering & Surveying 119 S Green St, Sonora 95370 | (209) 532-7491 |
| Frank Walter & Assoc 105 S Stewart St, Sonora 95370 | (209) 532-5173 |
| Gjf Engineering 188 Bradford St, Sonora 95370 | (209) 532-1867 |
| Golden State Surveying Eng 488 S Stewart St, Sonora 95370 | (209) 533-4797 |
| Charles Patterson 20135 Sommette Dr, Sonora 95370 | (209) 532-6859 |