Houserock Rapid — Houserock Wash becomes Rider Canyon and ends at Houserock Rapid with a nice accessible beach area. In early historic times the discovery of this access is associated with the Stanton survey. Expedition photographer F.A. Nims was seriously injured somewhat upriver from this location and was taken out through a break in a crevice in the upper canyon on the west wall — the way up is very steep and there are several minor climbs and passing under boulders in the upper cliff. One of the crew wrote "...his description of the places over which we would have to carry our unconscious companion, was, to say the least, not ecouraging." For any adventurous backpacker the trip should be great fun and today fishermen still go this way to fish the Marble Canyon trout — some big ones are often seen in the shallows above the rapid.

Routes — Good dirt-road access to the trailhead, see Michael Kelsey's guide for road directions, but his notes about a big chockstone without any bypass are not true. There is one bypass that seems unlikely from above and several pools and ledges to deal with. Upriver along the riverbank does not appear to work. Downriver goes quite well to Boulder Narrows and the engineers route at mile-19.

2009 October - Descend Nims route, overnight at the river, downriver and out at mile-19.