Many firms count oil and gas companies, as well as electric, gas, and water utilities, as major clients. Typically working under a Master Services Agreement or similar type of contract, a wide range of engineering services are provided to these clients, including civil, mechanical/electrical, structural, environmental, geotechnical, and water-related design. Energy and utility clients are also significant buyers of surveying and mapping services, because their projects often span large geographies. The power market is comprised of electric, distribution, gas, and oil. Facilities include power plants, nuclear reactors, hydroelectric plants, thermal, wind and solar. The distribution sector includes electrical substations, switch houses, transformers, and transmission lines. The water supply market consists of plants, wells, lines, pump stations, reservoirs, tanks, and towers.