Carollo Engineers is an environmental engineering consulting firm that specializes in the planning, design, and construction of water and wastewater facilities. The company was founded in 1933 and is headquartered in Seattle, Washington. Carollo Engineers has over 40 offices throughout the United States and provides services to clients in the municipal, state, and federal government sectors, as well as private industry. The company's services include water treatment, wastewater treatment, water resources planning, and environmental compliance. Carollo Engineers has received numerous awards for its work, including the American Council of Engineering Companies' Grand Conceptor Award.