Donald John Koski, age 82, passed away peacefully on March 11, 2026. In his final days, many family members and friends were able to visit and spend meaningful time with him.

Don was born in 1943 in Ironwood, Michigan, and carried his love for the outdoors and strong work ethic throughout his life. He spent many years as a dedicated biology teacher in Wisconsin Rapids, WI, where he inspired countless students with his passion for science. He was known for his famous 'grub worm cake,' that his students loved!

In the early 1980s, he combined his scientific knowledge with an entrepreneurial spirit to build a mushroom farm from the ground up, founding Heartland Mushrooms. What began as an idea from his knowledge of biology, grew into a successful farm and a testament to his ingenuity and determination.

Don also enjoyed traveling. He traveled with his daughter to Guatemala when adopting her children, and later traveled to Finland with his beloved sister, a trip that was especially meaningful to him.

Later in life, Don moved to Lake Wisconsin, where he remodeled his lake house and enjoyed boating and time on the water with his beloved partner, Barb McGill. Many evenings were spent watching the sunset together on the pontoon with a cold beer, appreciating the quiet beauty of the lake.

Don also enjoyed spending time with friends at the Waddle Inn, where he developed many lasting friendships. Known for his comical personality, he was also known for repeatedly being the winner of the monthly drawing-something his friends never let him forget.

Don is survived by his children, Brian Koski, Pamela Koski, and Stephanie Koski; his grandchildren, Kade Koski and Elli Koski; his great-granddaughter, Angel Sparks; and his sisters, Elaine Jegi and Marlene LaBlonde.

He will be remembered for his love of family, his adventurous spirit, and the many lives he touched as a teacher, businessman, and friend.

A celebration of life will be held at ANCHOR AT LAKESIDE BAR & GRILL, W10960 Corning St., Poynette, Saturday, March 28, 2026, from 1 p.m. to 4 p.m.

For more information and online condolences please visit www.gundersonfh.com

Gunderson Lodi

Funeral & Cremation Care

157 S. Main St.

(608) 592-3201

Donald J. Koski

March 20, 1943 - March 11, 2026

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