Yes, it is absolutely still enforceable.  If the move took place less than six months ago, it can still be enforced in South Carolina, because Utah does not become the children's home state until they have been there that long.

The modern trend in family law is to give the divorced custodial parent more freedom to move with her/his children to another state.  However, that's usually conditioned on making appropriate adjustments to the parenting time or visitation schedule because alternating weekends and one overnight in the middle of the week just isn't realistic in most interstate situations.  The visitation is usually put into fewer, but longer, stretches of time, during summer and holiday school breaks, and often both sides have to contribute to the travel costs involved.

Once a state court has made a custody determination, that state keeps jurisdiction over all matters concerning that child, unless:

1. A court of the state with jurisdiction determines that the child or the child and a parent do not have a significant connection with the state, and evidence concerning the child's custody determination is not available in the state;

2. A court of the state with jurisdiction, or any other state, determines that the child and both parents or acting parents do not reside in the state any longer.

Once a custody determination has been made, a court of another state does not have authority to modify the determination, unless the state with jurisdiction determines that it does not have jurisdiction as noted above, or any state court determines that the child, parents, and any acting parents do not reside in the state which currently has jurisdiction.