Between 1880 and 1935 Nahl was a prolific exhibitor throughout California and his oil paintings, drawings, charcoals, prints (especially monotypes, etchings, and lithographs), sculptures, and watercolors were consistently well received. Among his many awards was the bronze medal at Seattle’s Alaska-Yukon-Pacific Exposition in 1909 for his painting "The Silence". In 1915 at the Panama-Pacific International Exposition (PPIE), Nahl’s "13th Labor of Hercules" lithographic poster was given a first prize and selected as the official image, which was featured on maps, book covers and catalogues of the Exposition, advertised worldwide. The image features a muscular male nude straddled between two bodies of land symbolizing the Culebra Cut in the Panama Canal. Also at the Exposition he received a bronze medal for his “psychological study” in oil titled "Despair" and a silver medal for his thirteen etchings. In 1926 he received a prize from the California Society of Etchers.