Tetra Tech is a company that provides consulting and engineering services focusing on water, the environment, sustainable infrastructure, renewable energy, and international development. It operates through two segments: Government Services Group (GSG) and Commercial and International Services Group (CIG). The GSG segment offers consulting and engineering services in water, environment, sustainable infrastructure, information technology, and disaster management. The CIG segment includes environmental, design, planning, architectural, sustainable engineering, geotechnical, project management, and other services. The company serves the commercial and government sectors.