Alliant Energy's top executive says he will retire at the end of March.

William D. Harvey has served as the Madison-based energy company's chairman and chief executive officer for the last six years. He has been with the utility and its predecessor, WPL Holdings, for 25 years.

The company's board of directors has appointed 52-year-old Patricia Kampling to succeed Harvey. She will take over as chief executive officer, president and board chairwoman on April 1.

Kampling joined Alliant in 2005. She currently serves as president and chief operating officer. She also sits on the American Transmission Company and Briggs & Stratton Corporation boards.