X0203 3 2011-03-11 0 0001441849 CLOUD PEAK ENERGY INC. CLD 0001514965 VOORHEES JAMES S 505 S. GILLETTE AVE. GILLETTE WY 82716 1 Common Stock 6250 D Exhibit 99.1 - Power of Attorney /s/ Amy J. Stefonick, attorney-in-fact for Mr. Voorhees 2011-03-14