From Ebay where a ca. 1908 postcard, apparently from grand opening ceremonies, was for sale:
"Christian Harader, a Dunkard Minister, built the Dunkard Mill on the Walnut river in 1874, northeast of Arkansas City. He was a member of the Dunkard sect, which believed in a full beard for men. Harader was one of a sizable colony of the Order living in that vicinity.
"The second stone bridge Cowley County ordered was to be the largest stone arch bridge in Kansas. The Dunkard Mill Bridge was built over the Walnut River outside of Arkansas City. With three 50-foot-span arches, it was to be a monolithic structure. Later, due to the insufficient waterway of the original design, a fourth, smaller arch was added. The bridge stood for a few decades before being destroyed by a devastating flood in April of 1944."