EXHIBIT 21 SUBSIDIARIES OF WISCONSIN POWER AND LIGHT COMPANY The subsidiaries and affiliates of WP&L as of December 31, 1997, were as follows: Name of Subsidiary % of Voting Stock Owned Directly or Indirectly by the Company State of Incor. A. South Beloit Water, Gas and Electric Company (100%) Illinois B. REAC, Inc (100%) Wisconsin C. Wisconsin River Power Company (33-1/3%) Wisconsin D. Wisconsin Valley Improvement Company (13%) Wisconsin