Overview
Harmon Tunnel: The only highway tunnel in Iowa , greets all visitors entering the park. The tunnel pierces the base of the limestone backbone and provides access to the remainder of the park facilities. Historical Note: In 1858 the tunnel was originally dug by William Harmon and his sons as a small chute to carry water diverted from Middle River to power a saw mill that was eventually converted to a grist mill. The mill was abandoned in 1904 and the tunnel expanded in size to allow vehicle traffic in 1925. The tunnel has since been expanded and reinforced to accommodate modern vehicles.
Middle River & Limestone Backbone: Middle River makes a great horse-shoe loop in the park. The dividing wall is called the backbone which is a natural limestone ridge over 100 feet high. When standing atop the backbone directly over the tunnel, you can see Middle River flow in all four directions. The geology of the backbone is as extensive as the plant life and well worth exploring.
Middle River Ford: Built in the 1920’s, the ford is the only means of vehicle access (within the park) to the west side of the park. During normal river flow levels, vehicles can safely cross the ford which maintains a depth of 2” to 4”. The ford has provided countless hours of recreation for many generations of park visitors who love to wade, splash and fish in and around the structure. The ford is closed during high water flows and icy conditions during winter months.