AltaGas Ltd. Receives Approval from the Regulatory Commission of Alaska and Expects to Close US$1.135 Billion SEMCO Acquisition on August 30, 2012

CALGARY, ALBERTA--(Marketwire - Aug. 15, 2012) - AltaGas Ltd. ("AltaGas") (TSX:ALA) (TSX:ALA.PR.A) (TSX:ALA.PR.U) (TSX:ALA.R) today announced that the Regulatory Commission of Alaska approved the application for AltaGas to acquire SEMCO Holding Corporation ("SEMCO"). All regulatory approvals have now been received and subject to customary closing conditions the acquisition of SEMCO (the "Acquisition") is expected to close on August 30, 2012.

"We are pleased to have received the final regulatory approval for this transaction and for the support shown by the regulators in both Michigan and Alaska," said David Cornhill, Chairman and CEO of AltaGas. "We look forward to the completion of this acquisition as it represents a significant milestone in our vision to be one of North America's leading energy infrastructure companies."

The addition of SEMCO to AltaGas' diversified portfolio of energy infrastructure assets is expected to be accretive to earnings and cash flow per share by more than 10 percent, and is expected to add approximately US$130 million in incremental EBITDA in 2013 the first full year of ownership.

AltaGas previously announced the proposed acquisition of SEMCO on February 1, 2012, subject to receipt of all regulatory approvals and satisfaction of various conditions to closing. SEMCO is the sole shareholder of SEMCO Energy Inc., a privately held regulated public utility company headquartered in Port Huron, Michigan. SEMCO owns a regulated natural gas distribution utility in Alaska known as ENSTAR Natural Gas Company and an interest in a regulated natural gas storage utility in Alaska under construction called Cook Inlet Natural Gas Storage Alaska, LLC. SEMCO also owns a regulated natural gas distribution utility and an interest in a natural gas storage facility in Michigan.

Subscription Receipts

Concurrent with the closing of the Acquisition and upon satisfaction of certain escrow release conditions, each subscription receipt issued by AltaGas on February 22, 2012 to fund the Acquisition will be converted, without payment of additional consideration or further action by the holder, into one common share of AltaGas. In addition, a dividend equivalent payment of $0.69 per subscription receipt will be payable to holders of record of subscription receipts on August 30, 2012, in respect of the dividends declared by AltaGas for the months ending February 28, 2012 through July 25, 2012, net of applicable withholding taxes.

Holders of subscription receipts on August 30, 2012, will also be eligible to receive the August dividend of $0.115 per common share payable on September 17, 2012.

AltaGas anticipates that the subscription receipts register will close at 4:30 p.m. (MST) on August 29, 2012 and the common shares to be issued in respect of the subscription receipts will be listed and posted for trading on the Toronto Stock Exchange on August 30, 2012. The subscription receipts are expected to be halted on August 30, 2012 and delisted at the close of business.

AltaGas is an energy infrastructure business with a focus on natural gas, power and regulated utilities. AltaGas creates value by acquiring, growing and optimizing its energy infrastructure, including a focus on renewable energy sources. For more information visit: www.altagas.ca.

This news release contains forward-looking statements. When used in this news release, the words "may", "would", "could", "will", "intend", "plan", "anticipate", "believe", "seek", "propose", "estimate", "expect", and similar expressions, as they relate to AltaGas or an affiliate of AltaGas, are intended to identify forward-looking statements. In particular, this news release contains forward-looking statements with respect to, among other things, business objectives, expected growth, results of operations, performance, business projects and opportunities and financial results, including specifically the closing of the Acquisition, expectations regarding the impact of the Acquisition on earnings, cash flow per share and EBITDA in 2013and the conversion of subscription receipts to common shares. These statements involve known and unknown risks, uncertainties and other factors that may cause actual results or events to differ materially from those anticipated in such forward-looking statements. Such statements reflect AltaGas' current views with respect to future events based on certain material factors and assumptions and are subject to certain risks and uncertainties, including without limitation, changes in market, competition, governmental or regulatory developments, general economic conditions and other factors set out in AltaGas' public disclosure documents. Many factors could cause AltaGas' actual results, performance or achievements to vary from those described in this news release, including without limitation those listed above. These factors should not be construed as exhaustive. Should one or more of these risks or uncertainties materialize, or should assumptions underlying forward-looking statements prove incorrect, actual results may vary materially from those described in this news release as intended, planned, anticipated, believed, sought, proposed, estimated or expected, and such forward-looking statements included in, or incorporated by reference in this news release, should not be unduly relied upon. Such statements speak only as of the date of this news release. AltaGas does not intend, and does not assume any obligation, to update these forward-looking statements. The forward-looking statements contained in this news release are expressly qualified by this cautionary statement.