Canal Lake Concrete Arch Bridge, Concrete arch bridge in Kawartha Lakes, Canada

Canal Lake Concrete Arch Bridge is a closed-spandrel arch bridge built in 1905, carrying a 16-foot-wide deck 202 feet over a portion of Canal Lake on the Trent-Severn Waterway. Its single arch has a radius of 30 feet and 29 feet of vertical clearance for boats. Curved steel girders reinforce the concrete, and the spandrel walls are marked to imitate voussoir stonework.

Built in 1905, it was Canada's first reinforced concrete arch bridge, using the Melan system with curved steel girders embedded in concrete. This construction method set new standards for bridge building across North America.

A plaque unveiled on 30 August 2008 by Bruce Stanton, MP for Simcoe North, stands on the southwest side of the bridge for the Historic Sites and Monuments Board of Canada. It records the structure as a milestone in Canadian civil engineering that led to large-span reinforced concrete bridges.

The bridge is open to vehicle traffic and provides about 29 feet (9 meters) of clearance for boats and watercraft on the waterway below. A full renovation in 2018 ensures the structure remains in good working condition for both functions.

The bridge uses a modified Melan system where carefully placed steel reinforcements reduced concrete use while maintaining full strength. This innovative approach demonstrated how engineers could be economical with materials without compromising safety or lifespan.