- The 300 Committee
- Alliance to Protect Nantucket Sound
- Biodiversity Works
- Brewster Flats
- Buzzards Bay Coalition
- Cape Cod Bay Watch
- Cape Cod Commercial Fishermen's Alliance
- Cape Cod Museum of Natural History
- COASTSWEEP
- Friends of the Cape Cod National Seashore
- Friends of Myles Standish State Forest
- Friends of Hawksnest State Park
- Green Burial Massachusetts
- Harwich Conservation Trust
- Herring Ponds Watershed Association
- Herring River Restoration Committee
- Jones River Watershed Association
- Keep Massachusetts Beautiful
- Mass Audubon
- Mass Climate Action Network
- Massachusetts Department of Conservation and Recreation
- Massachusetts Humane Society
- Massachusetts Water Watch Partnership
- National Marine Life Center
- Native Tree Society
- The Nature Conservancy
- Neponset River Watershed Association
- New England Coastal Wildlife Alliance (NECWA)
- NOAA
- North and South Rivers Watershed Association
- Orenda Wildlife Trust
- PACTV Community News
- Roger Williams Park Zoo
- Save the Bay - Narragansett Bay
- SEMPBA
- Sierra Club
- South Shore Natural Science Center
- Sustainable Cape
- Taunton River Watershed Alliance
- The Thornton Burgess Society
- Tidmarsh Farms
- The Trustees of Reservations
- Toxics Action Center
- U.S. Fish and Wildlife Service
- Vineyard Conservation Society
- Waquoit Bay National Estuarine Research Reserve
- Waquoit Bay Reserve Foundation
- Wareham Land Trust
- Watershed Action Alliance of Southeastern Massachusetts
- Westport River Watershed Alliance
- Wild Care, Inc.
- Wildlands Trust of Southeastern Massachusetts