Duncan Wohlgenant, 79, of Miles City, passed away peacefully on August 24, 2026, surrounded by family. Duncan was born on May 16, 1947, in Miles City to Joe and Lillian Wohlgenant, and was the oldest of three children. Growing up on the family ranch near Kinsey, Duncan was active in 4-H and FFA, eventually becoming his chapter’s president. After graduating from Custer County District High School, Duncan attended Montana State University where he earned a degree in Chemical Engineering and was a member of Sigma Nu fraternity. Duncan married Deborah Arneson in Bozeman on September 23, 1967, and they had two sons, Dan and Andy. Duncan’s career began with Conoco, where he held various engineering and management positions in Oklahoma, Colorado, Montana, and Louisiana along with leadership posts in the United Kingdom and Malaysia before retiring. Duncan was a superb engineer and loved his work too much to stay retired. He contributed to Frontier Refining in Cheyenne and Suncor in Denver before joining the CHS Laurel Refinery in 2007 as an engineering consultant. At CHS, Duncan was able to develop several expansion projects and work closely with his son Dan. Despite an automobile accident in 2019, Duncan continued to work as an engineer until his passing.

Aside from his engineering work, Duncan was passionate about renovating homes with his wife Deb. Between Deb’s keen eye for design and Duncan’s skills, they restored several homes across the country during their travels, including two historic homes in Miles City. Duncan returned to his family ranch later in life and worked tirelessly to improve and preserve it for future generations. He took great joy in passing his deep knowledge of engineering, construction, and ranching to his sons and grandchildren.

Duncan is survived by his wife Deb; sons, Dan (Michelle) and Andy (Meredyth); grandchildren, Max, Brett (Daniel), Mia, Kort, and Tessa; siblings, Mike and Lee Ann; and was preceded in death by his parents, Joe and Lillian.

A public celebration of Duncan’s life will be held on September 16th from 4pm to 8pm in the banquet room of the Red Door Lounge in Billings, where he enjoyed many Friday evenings commiserating with his engineering colleagues; a private interment will follow.

The family wishes to thank his caregivers at River Ridge Rehab & Nursing and Billings Clinic for their support and kindness.