There was a nice footbridge, but then the expected trail intersection was not on the other side. Farther South, just before the footbridge at the Lyell crossing, the trail crosses an area of solid rock, where there is no visible trail. After looking around, a trail appeared going West on the North side of the river. It was getting late, so the trail seemed like a good choice. The missing footbridge was discovered during the return trip.
Serendipitous wandering can sometimes be a fine substitute for precise planning.