Nicknamed "Ober", he was born and raised in Davenport, Iowa, but he lived most of his adult life in Minnesota.
Oberholtzer attended Harvard University and received a bachelor of arts degree, but left after one year of graduate study in landscape architecture.
During the period from 1908 to 1915, Oberholtzer wrote a number of articles and short stories, some under the penname Ernest Carliowa.
After plans were announced by business mogul Edward Backus to construct a series of dams to harness the Rainy Lake watershed for power generation, Oberholtzer spoke in opposition at a hearing of the International Joint Commission held at International Falls in September 1925.
As a result of meetings with Minneapolis businessmen who were similarly opposed to industrialization of the area, the Quetico-Superior Council was formed in 1928.