Montague, Ontario  Montague is a township in eastern Ontario, Canada, in Lanark County on the Rideau River. The township administrative offices are located on Roger Stevens Drive east of Smiths Falls. The township comprises the communities of Andrewsville, Atironto, Kilmarnock, Nolans Corners, Numogate, Poolers Corners, Rosedale and Welsh. Mother Tongue (2016 - single responses)  Language Spoken Most Often at Home (2016 - single responses)  The main roads in the township are the east-west County Road 43, the north-south Ontario Highway 15, and the northeast-southwest Roger Stevens Drive. The Rideau Trail passes through the township between Merrickville and Smiths Falls.