Dunnville is an unincorporated community of 6,000 people located near the mouth of the Grand River in Haldimand County, Ontario, Canada, near the historic Talbot Trail. It was formerly an incorporated town encompassing the surrounding area. Originally built as the entrance to the Welland "feeder" canal, the town once boasted several water-powered mills and a once-bustling canal port.
The feeder canal closed in the late 1880s and the last mill was destroyed and replaced with a condominium complex about ten years ago. There is an impassable dam at Dunnville which regulates the level of the Grand River at Port Maitland which, in the 19th century, also helped regulate the level of the Welland Canal (from 1829 until 1887 when the (3rd) canal began to intake its water directly from lake Erie).