Consider inquiring at the Utah Rivers
forum if you don't find the information or connections you're hoping for here.
Straight Canyon (Joe's Valley) of Cottonwood Creek
is a Central Utah gem for III-IV boulder garden creeking, but it's dam releases during runoff seem to typically hover just under runnable flows on normal years-- with an occasional lucky spike. Flow info here
. Seems like the legendary Johnny A runs it at like 180 cfs, but he finds stuff to boat on in Utah Valley 365 days a year, which is saying something. If it gets around 250 and you're in the area it may be worth going, especially if you like bouldering--at a minimum its pretty water and there's lots of cool rocks to climb on.
But snowpack is really bad in UT so you may be relegated to Green River Daily & Moab Daily for day trip options. I don't know much about Sevier. Muddy Creek isn't happening without a really big storm, and that means flash flood in a slot canyon--an insane place to be, and impassable roads when soaked anyway--so either way I wouldn't plan on it. Hasn't seen runoff since 2011 AFAIK.