Was thinking of doing this, but it looks like the park service has now banned this activity down there, which is a bummer, looks way sick! Glad you got to do it https://wwwnpsgov/grca/planyourvisit/upload/thunder_river_trailpdf

We are running it this weekend, too We also ran it at 500cfs 2 weekends ago Some of us went under that tree, which is arch-shaped, and others went around it Here is a video posted by a group that ran it in June 2011 at 1650cfs They all went around it: https://vimeocom/25878189

In one instance we were able to set up a kairn anchor A sandtrap wasn't at all required but would have made this little problem easier and cleaner On another we slung a flake in the wall I didn't really trust it because it sounded hollow so we backed it up with a very very solid 2 person body belay up canyon as we sent the heaviest person down first The back-up body belay anchor was kept until the last and lightest person rapped without it A pull cord was used to retrieve the webbing and allow someone else to enjoy...

https://wwweenewsnet/eenewspm/2017/07/05/stories/1060056973

https://wwwkslcom/sid=45457329&nid=148&title=woman-rescued-after-12-hours-stuck-in-san-rafael-desert-canyon

Not all dogs are good about it, but Lucy didn't mind rappelling Ruffware makes a climbing rated harness for dogs that has worked well for me https://ruffwearcom/collections/harnesses/products/doubleback-harness I always rappelled with her like I would an injured human parnter, with device extended above us and her at my side Worked well for us

It’s still banned: https://wwwfederalregistergov/documents/2017/07/06/2017-13891/notice-of-final-supplementary-rule-for-public-lands-in-the-moab-field-office-in-grand-county-utah

True For the protection of park resources,canyoneering groups are limited to amaximum of six people here is the reference if needed:https://wwwnpsgov/care/planyourvisit/upload/canyoneering-Apr16-low-res-locked-for-webpdf

I think coming back up would be pretty physical I remember a couple of tightish downclimbs that would probably be a little hard to reverse See this picture for the first of these: https://wwwroadtripryancom/go/tripimage/showphoto/2473 Take a rope just in case and give it a go! Coming back up would be a lot of fun to try

The link to the area overview at the top of the page has quite a bit of info:https://wwwroadtripryancom/go/a/utah/robbers-roost/Or zoom out on the google map for broader perspective