See http://www.cacreeks.com/tuol-lum.htm for a description of the run.
See http://www.boof.com/forums/viewtopic.php?t=1732&view=next&sid=c94e30358c9bd6452a3987f4cc25f89c for a short discussion.
On June 26, 2005, Michael Wallace Eckert was rafting with four friends on the Lumsden section of the Tuolumne River in California. When the raft hit Gray's Grindstone Rapid, Eckert fell out. At high water, Grey's Grindstone begins with a large river-wide hole, followed by a kilometer of rapids. Eckert apparently died of flush drowning. Authorities pulled his body from the river hours later.