"If promised, vacation must be granted. Although no Utah law requires private sector employers to provide employees with vacations, paid or unpaid, most employers do offer their employees some version of vacation. Thus, it is important for employers to remember that if they “promise” vacation, they may be legally bound to provide it--and that a binding promise does not require embodiment in a formal employment contract. Under some circumstances, an employer's assurance of paid vacation time, whether made in an employee handbook, given orally, or simply understood as a matter of consistent practice, may constitute an implied contract that is binding and enforceable."

http://www.blr.com/HR-Employment/Benefits-Leave/Vacations-in-Utah#/