| Business | Phone |
| Advanced Infrastructure System 8428 La Mesa Blvd, La Mesa 91941 | (619) 670-3393 |
| Baird Engineering 4939 Garfield St, La Mesa 91941 | (619) 460-6989 |
| Draper Engineering Po Box 3346, La Mesa 91944 | (619) 464-6528 |
| Snipes-Dye Assoc 8348 Center Dr # G, La Mesa 91942 | (619) 697-9234 |
| William A Steen & Assoc 8580 La Mesa Blvd # 102, La Mesa 91941 | (619) 460-9000 |