Slow down buddy. I don't know where you got your old text, but this is how it now reads. Discharge, not possession.
http://www.rules.utah.gov/publicat/code/r651/r651-612.htm
As in effect on May 1, 2008
R651-612-1. Unlawful Discharge of Weapons or Firearms.
The
discharge of weapons or firearms, including air and gas powered types, and all other devices capable of launching a projectile which could immobilize, injure, or kill any person or animal or damage property are prohibited in the park system unless:
(1) The weapon or device is being used for the legal pursuit of wildlife as per R651-614.
(2) The use of the weapon or device is authorized by a Special Use Permit or an authorized event as per R651-608.
(3) The weapon or device is used in accordance with UCA 53-5-701 Concealed Weapons Act, or UCA 76-2- 402, 76-2-403, or 76-2-405.
(4) The weapon or device is being used by authorized law enforcement officers in the performance of their official duties in accordance with UCA 76-2-402.