The Tonawanda was designed by Chief of Naval Engineering John Lenthall. Lenthall actually designed four monitors at that time. The Monadnock and the Agamenticus were the first and are considered the two Monadnock-class vessels. Lenthall altered the designs of the next two, the Miantonomoh and the Tonawanda and dubbed them the Miantonomoh-class. Because of the similarities between the two classes they are sometimes referred to collectively as the Miantonomoh-class.