The Nature Conservancy announced plans on Tuesday to buy four Kennebec River dams from Brookfield Renewable Energy. The Nature Conservancy said it planned to restore the Kennebec River to its pre-dam state. (Joe Phelan/Staff Photographer)The Nature Conservancy plans to buy four Kennebec River dams from Brookfield Renewable Energy in a move that could reshape the ecology and economy of one of the state’s largest watersheds. The Nature Conservancy said in a prepared statement Tuesday that it planned to restore the Kennebec River to its pre-dam state. AdvertisementEnvironmental groups have long argued for the removal of the four Kennebec River dams, which are located in Waterville, Winslow, Fairfield and Skowhegan.