Constructed in 1949, the existing Bayfield River Bridge is a 70-metre long, two-span, deck-truss bridge. Highway 21 is a two-lane undivided highway, with one lane in each direction traveling in a north/south direction. The Bayfield River flows westward into Lake Huron. The posted speed limit at the bridge is 60 km/hr. A sidewalk is located on the west side of the structure but there are no sidewalk connections on the approaches. The existing bridge has reached the end of its service life and will be replaced with a new structure.

The approved project involves a complete replacement of all bridge components, improvement to the vertical alignment to meet hydraulic requirements, embankment widening, pavement reconstruction/rehabilitation, drainage improvements, replacement of sidewalk, and replacement of curb, gutter and guide rail on approaches. The new bridge will be a single-span half-through arch bridge on the same alignment, and will include a two 3.75-m travel lanes, 2.5-m paved shoulders, 2.0-m sidewalk on the west side of the bridge, and an open railing barrier. Construction staging at the bridge will involve a full closure with on-site detour via a temporary modular bridge. The temporary bridge will be constructed on the west side of the existing bridge location to maintain two lanes of traffic on Highway 21. Throughout construction, pedestrian passage will be accommodated through the site on the temporary modular bridge.