TriSummit Utilities Inc. announced that the Regulatory Commission of Alaska (RCA) approved the joint application of its wholly-owned United States subsidiary, Alaska Utility Holdings Inc. (AUHI), and SEMCO Energy Inc. (SEMCO), a wholly-owned United States subsidiary of AltaGas Ltd., for AUHI to acquire ENSTAR Natural Gas Company, the Alaska Pipeline Company, the Norstar Pipeline Company and a 65% indirect interest in Cook Inlet Natural Gas Storage Alaska, LLC from SEMCO, subject to certain customary conditions and post-closing filing requirements.