I am going to cancel a Middle Fork Salmon permit today that is set for the Saturday of Memorial Day, 5/26. Technically, the date is "pre-launch control season" as the lottery dates started on 5/27 this year, but it still seemed like a primo date. We got lucky with the Selway and have a permit launch on the Selway set for 5/27, and I don't think I'll be able to run the MFS in one day and then make it to the Selway the next. So, it looks like we're going to take our chances on the Selway flow, even though the snotel gauges are still going up, and cancel this permit and pray the Selway isn't raging out of control on the 27th.
Incidentally, we do have some room on the Selway permit, but you'd have to be able to make a very last minute decision (the rafters are out if it's significantly over 5') and deal with a wishy washy group that has a hard time making decisions. PM me if you're interested, but be aware I don't have a lot of information on the Selway trip at the moment and will be pulling it together last minute if the water levels look ok.
Anyhow, for the MFS cancellation, the recreation.gov website has this to say about cancellations, "Cancellations are reissued at Federal recreation, camping and tour reservation information - Recreation.gov
. Cancellations will be posted at a random time on the website within 24 hours of being released."
In my experience they post fairly quickly (although with this being a Saturday, maybe it will take longer), so I'd keep an eye out fairly soon. I'll be cancelling it at 8:30 am MST. Good luck.