Wisconsin Power and Light: Files request to adjust electric rates

Media Contact: Scott Reigstad (608) 458-3145

Investor Relations Contact: Susan Gille (608) 458-3956

Filing necessary due to new PSCW fuel rules and projected fuel costs

MADISON, Wis. – May 18, 2011 – Wisconsin Power and Light Company (WPL), a subsidiary of Alliant Energy Corporation (NYSE:LNT), filed a request today with the Public Service Commission of Wisconsin (PSCW) to implement a rate adjustment for 2012.

Specifically, WPL is requesting an overall 2012 increase of 1.3% for electric retail customers. The rate adjustment request was filed because projected fuel costs for 2012 exceed the amounts currently being recovered in base rates. Under WPL’s 2012 request, residential customers using 600kWh of electricity per month would see a monthly increase of 81 cents on their bills, effective January 2012.

“We continue to aggressively manage our expenses to improve the competitiveness of our rates and minimize rate increases,” said John Larsen, WPL President. “Even with this rate increase request, our company would have among the lowest residential electric rates in the state compared to other Wisconsin investor-owned utilities.”

WPL’s rate adjustment filing is based upon a proposed fuel cost plan for calendar year 2012 that is required under new PSCW fuel rules. The new fuel rules require WPL to defer any fuel cost changes outside of a range approved by the PSCW during the year. Any remaining difference at the end of the year will be considered for inclusion in a future rate adjustment case, provided WPL’s earned return on equity (ROE) does not exceed its authorized ROE. WPL believes this process decreases the number of fuel cost filings utilities make, reduces staff time and resource burdens on the PSCW, customer interveners and utilities, and provides appropriate protections for customers and utilities.

WPL has no plans at this time to file any additional retail rate increase requests for 2012. All rate changes must be approved by the PSCW after a thorough review of the data and after obtaining public input. The approval process for the rate increase request is expected to take several months, with new rates becoming effective on or about January 1, 2012.