Dr. Gearheart teaches courses in environmental impact assessment, hazardous waste management and water quality management.
His research interests include water and wastewater treatment, using appropriate technology, including constructed wetlands. He is also involved with a number of public and private sector agencies providing support for water supply facilities in developing countries, such as Indonesia, Kenya, Ghana, and Sierra Leone.
Dr. Gearheart is involved with the development of Arcata's Integrated Wetland and Wastewater Treatment Facility and the Arcata Marsh. The Arcata Marsh serves as a sewage treatment plant, a recreation area, a wildlife sanctuary and aquaculture project.