WILLMAR — The Willmar City Council on Monday approved several items related to the construction of the $3.1 million Robbins Island Regional Park amphitheater project. The project has been a collaborative effort of the Willmar Rotary Club, Willmar city staff and Engan Associates. The Willmar Rotary Club — in collaboration with the city of Willmar — has been planning for this project for several years, initially presenting the design plans for the…