Casco Bay Estuary Project
- Mission is to preserve the ecological integrity of Casco Bay. Provides information about stormwater, stewardship, toxics, projects, and water quality.
- http://www.cascobay.usm.maine.edu/

Students for the Protection of Island Ecology
- Students from Portland High School conducting ecological studies and stewardship activities on the Casco Bay Islands.
- http://www.cascobay.com/educ/spie/

Friends of Casco Bay
- Public advocacy group working to improve and protect the environmental health of Casco Bay through education, and stewardship. Features history, resources, description, membership fees, projects, and programs offered.
- http://www.cascobay.org/