 FERGUS FALLS, Minn.--BUSINESS WIRE--Otter Tail Corporation Nasdaq: OTTR today announced financial results for the quarter ended March 31, 2021. SUMMARY Consolidated operating revenues increased 11.5 to 261.7 million. Consolidated net income increased 25.0 to 30.3 million primarily driven by strong Plastics segment performance. Diluted earnings per share increased 21.7 to 0.73 per share. The corporation increases its 2021 diluted earnings per share guidance range to 2.47 to 2.62 refl 