| Business | Phone |
| Carto Remote Sensing 215 W San Antonio St 102, San Marcos 78666 | (512) 392-7745 |
| Eardc Laboratory 601 University Dr, San Marcos 78666 | (512) 245-3545 |
| Environmental Pr 323 W Hopkins St, San Marcos 78666 | (512) 393-5090 |
| Environmental Projection Syst 101 Uhland Rd, San Marcos 78666 | (512) 353-3137 |
| Environmental Sciences 818 Palomino Ln, San Marcos 78666 | (512) 392-4818 |
| Esa Environmental Svc 4105 Hunter Rd # 4, San Marcos 78666 | (512) 392-1222 |
| Hays Environmental Consulting 301 N Guadalupe St 107, San Marcos 78666 | (512) 392-3546 |
| Whitenton Group 325 E Hopkins St, San Marcos 78666 | (512) 353-3344 |