The structure of this waterfall will vary almost every time you see it. It typically thaws and refreezes numerous times over the course of the Minnesota winter. At the start of this season (Jan. '09) it was one pillar and now it is late February and it covers the whole face like the water runs during the summertime.
Rangers informed me that using the bridge as an anchor is okay with them. Bring very long pieces of webbing or similar anchoring material and just use the bridge. There are also a couple of trees if you don't have long enough material to utilize the bridge.