 The construction of the Amelia Earhart Dam in 1966 has converted it to freshwater and maintained a fairly constant depth.The Amelia Earhart Dam, situated on the Mystic River below the mouth of the Malden River, converted the Malden River from a brackish, tidal river, to a non-tidal freshwater river when it was constructed in 1966.The dam was more sophisticated than the simple iron gates of the Craddock Locks, which it replaced.