| Business | Phone |
| County Probation Office 700 N L B J Dr 112, San Marcos 78666 | (512) 353-8923 |
| Material & Test Div 5702 S I H 35, San Marcos 78666 | (512) 396-3919 |
| Resource Protection Lab 505 Staples Rd, San Marcos 78666 | (512) 353-3486 |
| River Studies Program 505 Staples Rd, San Marcos 78666 | (512) 353-3480 |
| River Studies Program 901 Aquarena Ctr, San Marcos 78666 | (512) 754-6844 |
| Texas Program Director 507 Staples Rd, San Marcos 78666 | (512) 353-0313 |
| Transportation-Mntnc Warehouse 1710 Highway 21, San Marcos 78666 | (512) 353-1061 |