Alliant Energy Subsidiaries Successfully Complete Divestiture of Illinois Assets

MADISON, Wis., Feb. 6 /PRNewswire-FirstCall/ — Alliant Energy Corporation’s (NYSE:LNT) utility subsidiaries, Interstate Power and Light Company (IP&L) and Wisconsin Power and Light Company (WP&L), announced today that the companies have successfully closed the sale transactions of its Illinois assets to Jo-Carroll Energy, Inc. (JCE) and Rock County Electric Cooperative Association (RCECA).

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IP&L divested its electric distribution and natural gas utility business assets located in Illinois to JCE. Net proceeds from the transaction are approximately $28 million. JCE is a not-for-profit, electric distribution cooperative providing electric distribution and natural gas utility services to customers in Jo-Daviess, Carroll and Whiteside counties.

WP&L sold its South Beloit Water, Gas and Electric Company’s (SBWGE) electric and natural gas assets to RCECA. Net proceeds from the transaction are approximately $23 million. SBWGE currently provides electric and natural gas services to customers in north-central Illinois. RCECA is a Wisconsin Membership Cooperative currently providing electric distribution service to customers in Illinois and Wisconsin.

Customers impacted by IP&L’s and WP&L’s divestiture of its Illinois assets will receive additional information regarding the sale transaction in the next several weeks.

Former IP&L customers can contact JCE at 1-800-858-5522 and former SBWGE customers can contact RCECA at 1-866-752-4550 for questions or concerns regarding their accounts.

“Our company is pleased that the sale of our Illinois electric distribution and natural gas utility assets is completed,” says Barbara Siehr, vice president of customer service – Alliant Energy. “The sale of our Illinois assets is good for our former customers and shareowners. The transactions recognize JCE’s and RCECA’s commitment to provide our former customers in Illinois with continued access to safe and reliable energy service.”

In June 2005, the Alliant Energy subsidiaries reached definitive agreements to sell their Illinois electric and natural gas distribution assets to JCE and RCECA.

On January 3, 2007, IP&L and WP&L received approval from the Illinois Commerce Commission to sell the companies’ respective Illinois assets.

The Alliant Energy subsidiaries expect to use the proceeds from the divestitures to retire short-term debt.

Alliant Energy is an energy-services provider with subsidiaries serving approximately 1 million electric and over 420,000 natural gas customers. Providing its customers in the Midwest with regulated electric and natural gas service is the company’s primary focus. Alliant Energy’s utility subsidiaries are Interstate Power and Light and Wisconsin Power and Light companies. Alliant Energy, headquartered in Madison, Wis., is a Fortune 1000 company traded on the New York Stock Exchange under the symbol LNT. For more information, visit the company’s Web site at .