Fr. Ivan Nienhaus was born in New Hampton, Iowa, and raised in the small town of Ft. Atkinson near Decorah. Upon graduating from Turkey Valley High School, he attended the University of Iowa. He spent an additional year at Loras College in Dubuque studying philosophy prior to attending St. Meinrad School of Theology in St. Meinrad, Indiana.

He was ordained to the Priesthood at Nativity Parish in Dubuque on June 24, 1989. His first assignment was at St. Patrick Church in Cedar Rapids. He was then assigned to Sacred Heart Parish in Waterloo along with teaching responsibilities at Columbus High. He spent 10 years serving parishes in Winthrop, Masonville, and Monti, followed by a one-year stint at Immaculate Conception Church in Cedar Rapids. He next served at St. Cecilia Parish in Ames. He spent 11 years at St. Patrick Church in Cedar Rapids, which were rebuilding years following the Flood of 2008.  Fr. Ivan also served as the Catholic Priest Chaplain at St. Luke Hospital and Pastoral Coordinator of LaSalle Catholic School (Grades K-8) on the west side of Cedar Rapids.

Fr. Ivan joined Saint Patrick Church in Cedar Falls on Sept. 7, 2021.