SEMCO ENERGY, Inc. Announces Closing of Public Offering of Common Stock

PORT HURON, Mich., Aug. 15 /PRNewswire-FirstCall/ -- SEMCO ENERGY, Inc. (NYSE: SEN) today announced the closing of its public offering of 4,945,000 shares of common stock, including 645,000 shares issued upon the exercise of an option granted to the underwriters to cover the over-allotment, at a public offering price of $6.32 per share. The aggregate gross proceeds of the offering, including shares issued upon exercise of the over-allotment option, are $31.3 million, with net proceeds of approximately $30.0 million (after payment of underwriting discounts and commissions, but excluding estimated offering expenses).

Credit Suisse First Boston LLC acted as lead manager for the offering. Natexis Bleichroeder Inc. and A.G. Edwards acted as co-managers. Proceeds from the offering will be used to redeem the Company's outstanding 10.25% Series A Subordinated Debentures due 2040 held by an unconsolidated capital trust subsidiary, SEMCO Capital Trust I.

This communication shall not constitute an offer to sell or the solicitation of an offer to buy nor shall there be any sale of these securities in any state in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such state. A shelf registration statement relating to the shares of common stock that the Company has sold has previously been filed with, and declared effective by, the Securities and Exchange Commission. Any offer of shares of common stock will be made only by means of a prospectus, including a prospectus supplement, forming a part of the effective registration statement. Copies of the final prospectus supplement and accompanying prospectus may be obtained from Credit Suisse First Boston, Prospectus Department, 1 Madison Avenue, New York, New York 10010-3629 (212-325-2580).

SEMCO ENERGY, Inc. distributes natural gas to more than 404,000 customers combined in Michigan, as SEMCO ENERGY GAS COMPANY, and in Alaska, as ENSTAR Natural Gas Company. It also owns and operates businesses involved in propane distribution, intrastate pipelines and natural gas storage in various regions of the United States.

The following is a "Safe-Harbor" statement under the Private Securities Litigation Reform Act of 1995. This release contains forward-looking statements that involve risks and uncertainties. Statements that are not historic facts, including statements about the Company's outlook, beliefs, plans, goals and expectations, are forward-looking statements. Factors that may impact forward-looking statements include, but are not limited to, the effects of weather, the economic climate, competition, commodity prices, changing conditions in the capital markets, regulatory approval processes, success in obtaining new business, success in defending claims against the Company, and other risks detailed from time to time in the Company's Securities and Exchange Commission filings.

SOURCE SEMCO ENERGY, Inc.
08/15/2005

CONTACT: Analysts Contact: Thomas Connelly, Director of Investor Relations, Phone: 1-248-458-6163, or Media Contact: Timothy Lubbers, Director of Marketing & Corporate Communications, Phone: 1-810-887-4208, both of SEMCO ENERGY, Inc.

2330 08/15/2005 13:01 EDT http://www.prnewswire.com

"Safe Harbor" Statement under the Private Securities Litigation Reform Act of 1995: Statements in this press release regarding SEMCO Energy's business which are not historical facts are "forward-looking statements" that involve risks and uncertainties. For a discussion of such risks and uncertainties, which could cause actual results to differ from those contained in the forward-looking statements, see "Risk Factors" in the Company's Annual Report or Form 10-K for the most recently ended fiscal year.