PORTLAND — Back Cove residents have six months to raise $400,000 to buy Canco Woods and create a stewardship endowment, according to an agreement announced today by The Trust for Public Land.

The national nonprofit conservation organization has reached a deal with Union Power and Water, which earlier this year had planned to sell the 12.75-acre parcel to a developer.

Portland Trails is also involved in the effort to buy the parcel.

The developer, whose identity has not be disclosed, dropped plans to build on the parcel after neighbors began organizing a campaign to oppose the project and acquire the property.

It’s uncertain who would end up owning the parcel if it’s purchased. The Trust for Public Land could convey it to Portland Trails. If the city contributes any money, however, it would have to be owned by the city, said City Councilor Cheryl Leeman, who represents the district and also serves on the city’s Land Bank Commission.

Leeman said she is excited about the possibility of preserving the parcel from development and that she can facilitate conversations with the city about how the city could help in the purchase.

She said it’s important to keep the parcel in its natural wooded state rather than turn it into a manicured park with a green lawn and benches. She said she is hopeful that the neighborhood and other groups can raise the money.

“I will do anything I can as their representative to make sure this happens,” she said.