History of Tertiary Highway 813:
Tertiary Highway 813 was a temporary designation for a forest access road in the Sturgeon Falls area in the late 1970s and early 1980s. In 1979, a spring flood washed out the Crystal Falls Bridge over the Sturgeon River north of Sturgeon Falls. This bridge provided the only public road access from Highway 64 to Tomiko Lake and the small rural communities lying east of the Sturgeon River in Grant and Field Townships. The Ministry of Transportation and Communications (MTC) took action by designating 7 miles of a forest access road leading north from Highway 17 as a new Tertiary Highway. Parts of the road were privately-owned, and the highway designation was done in the interest of restoring temporary public road access to Grant & Field Townships. On June 7, 1979, a Designation Plan was prepared by the MTC showing the proposed designation of Riding Stable Road as a new Tertiary Highway. The route was formally designated as a Tertiary Highway by an Order-in-Council, effective June 27, 1979.
According to some MTC reports from the early 1980s, Riding Stable Road was numbered as Highway 813. The highway does not appear on any road maps, and it is uncertain if the highway was actually posted with Highway 813 route markers. If it was a posted highway designation, it would be the highest numbered provincial highway that Ontario has ever had. The Highway 813 designation proved to be only a temporary measure. In late 1980, the MTC relinquished jurisdiction and control over Riding Stable Road. The provincial highway designation was formally removed from Riding Stable Road by an Order-in-Council, effective October 16, 1980.