http://www.sageriders.com/ They have a link to the USRA, or join USRA.. . I don't have the USRA contact info, but I believe RimRock racing in SLC can hook you up.. They cover Moto, Dez, and Track for Utah.. I believe there were 8-9 dez races alone this year.. A few other Utah clubs are the Utah Desert Foxes, and the Buzzards MC..
The desert races are done this year, so you'll have to wait for the last weekend in february for the St. George race by the wizards. The Gran Prix series has been cancelled for next year, but there is a WORCS race in March in Price.
If ya wanna go ridin' sometime here in UT, lemme know. I'm planning on getting my new bike ('02 200 MXC) within the next month, so just give me a holler!
Jason