Carollo Engineers is an environmental engineering firm that specializes in the planning, design, and construction of water and wastewater facilities. The firm was founded in Phoenix, Arizona, in 1933 and counts the City of Phoenix among one of our original clients—a working relationship more than 80 years old! From that single office with three engineers, Carollo has grown to more than 800 people in 40 offices throughout the United States. Our staff includes civil, structural, electrical, mechanical, environmental, and instrumentation and control engineers, as well as scientists, planners, architects, and CAD designers.