The bridge piers and abutments appear to be poured concrete. While poured concrete was somewhat unusual for a bridge in the 1880s, the concrete appears aged enough to have been from that era. As a result, I am unable to tell if this is the original 1880 bridge, or if it is a newer structure. I would at least expect that the steel would have been replaced as trains became ever heavier in the early 1900s.
The two photos above and below are two views from early summer. The photo above is looking north from the Big Stone Lake Dam. The photo below is looking south from the new CSAH-30 Bridge.