Maine WasteWater Control Association
- Promotes environmental management practices to protect and improve the waters and related environments. Includes membership, position, calendar, and directory.
- http://www.mwwca.org/

Maine Coast Heritage Trust
- Conserving Maine shorelands and islands by working with communities and individuals along the coast. Links to Maine Land Trust. Newsletter and membership information.
- http://www.mcht.org/

Friends of Schoodic
- A non-profit organization dedicated to protecting the natural environment of the Schoodic District of Acadia National Park..
- http://www.friendsofschoodic.org/

Friends of Hog Island
- Non-profit dedicated to the preservation of the Audubon Camp on Hog Island and the support and enhancement of its educational goals.
- http://www.naturecompass.org/fohi/

Environmental Protection Agency Region 1: Superfund Site Index
- Places targeted in Maine for government sponsored toxic waste cleanup.
- http://yosemite.epa.gov/r1/npl_pad.nsf/SelectedByState?OpenForm&View=Maine

Penobscot BayWatch
- Protecting and restoring the ecology and environment of Penobscot Bay, through research, advocacy, and community empowerment.
- http://userpages.acadia.net/coastwatch/

Marine Environmental Research Institute
- Dedicated to researching pollution of the ocean, unsustainable coastal development, species and habitat degradation, and environmental emergencies (toxic spills, releases) affecting marine life.
- http://www.meriresearch.org/

Maine Environmental Policy Institute
- Dedicated to researching environmental challenges facing the state and reporting the research to policy makers and the public.
- http://www.meepi.org/

Lakes Environmental Association
- A private, non-profit organization founded in Naples to protect the water quality and watersheds of the Sebago-Long Lake Region. Covers the towns of Bridgton, Denmark, Harrison, Naples, Sweden, Waterford and Sebago Lake.
- http://www.megalink.net/~lakes/

Humboldt Field Research Institute
- Institute for the study of natural history in Maine.
- http://maine.maine.edu/~eaglhill/

Gulf of Maine Council
- Promotes stewardship activities in the Gulf of Maine and its watershed, to enhance environmental quality and secure resource use for all generations.
- http://www.gulfofmaine.org/

Echo Lake Association
- Property owners and other parties interested in lake quality in Fayette, Mt Vernon, and Readfield.
- http://www.echolake.org/

Biodiversity Research Institute: Loons
- Small, nonprofit group dedicated to progressive environmental research and education. Specialty is avian (bird) studies, and aquatic toxicology with a focus on the loon.
- http://www.briloon.org/