X0202 4 2006-04-10 0 0000075129 OTTER TAIL CORP OTTR 0001191499 NELSON KENNETH L 215 S CASCADE ST FERGUS FALLS MN 56537-2801 1 0 0 0 Common Stock 2006-04-10 4 A 0 2200 28.235 A 4100 D Shares of Common Stock acquired under the Corporation's Stock Incentive Plan, which is a grant of Restricted Stock. The 2,200 shares granted 4/10/06 have a grant price of $28.235 and vest at 25% yearly beginning 4/8/07. See below for other holdings: 1. Direct holding of 393 shares acquired under the 1999 Stock Incentive Plan as part of the Compensation Program for Outside Directors. 2. Direct holding of 1,146.4016 shares held in the Dividend Reinvestment Plan. 3. Direct holding of 1,200 shares which no longer carries the restriction. 4. 2,000 stock options with expiration date of 4/9/2010. 5. 2,000 stock options with expiration date of 4/8/2011. /s/ Kenneth L Nelson by Debra J Lill -POA 2006-04-12