In his spare time Kowalski enjoyed horse-breeding and riding, sailing, hiking and backpacking, his Harley-Davidison motorcycle and skiing. According to Chemical & Engineering News, "After his retirement in 1999, Kowalski joined the Fort Lewis Mesa fire department in Durango, Colo., where he specialized in the handling of hazardous materials. Kowalski and his companion dog, Chaco-Bob, were a key part of the district’s canine search and rescue program."