Formed in 1982, the Zambezi Society is a conservation organisation which focuses its efforts solely on conserving wildlife and wilderness in the Zambezi Valley. "Our mission is to promote the conservation and environmentally sound management of the Zambezi River and its catchment area for the benefit of wilderness, wildlife and people."

The Cathance River Education Alliance was created in 2000 as part of a land-use agreement between Highland Green Developer John Wasileski and the Topsham Citizen group, Topshams Future. It quickly became a living partnership that included the Brunswick-Topsham Land Trust, area educators, various members of Highland Green residents and interested area citizens.