Leo Jan Clark

Leo Jan Clark, born on January 10, 1939, in Trenton, NJ, passed away suddenly due to natural causes on August 16, 2025, in Georgetown, DE. A distinguished figure both personally and professionally, Leo dedicated the majority of his career to public service, where he supervised and mentored field and engineering-oriented staff in the Environmental Protection Agency’s Water Pollution Division for 25 years. His expertise and intellect led to substantial advancements in the development of complex mathematical models of significant waterways, including the Potomac, Delaware, and Susquehanna Rivers, as well as the Chesapeake Bay.

Leo was a proud graduate of the University of Maryland, College Park, where he earned his Bachelor's degree in Engineering. His dedication extended beyond academia; he served honorably in the Public Health Service during the Vietnam War, where he conducted critical testing and assessments following military operations in the Nevada desert.

In his personal life, Leo was a faithful Catholic and devoted family man who cherished every moment spent with his loved ones, particularly during family gatherings and holidays. His loyalty and dependable nature were evident in the care he took, ensuring that his daughter and grandsons were supported in the years following his son-in-law, Christopher Wheeler's, passing. Leo was also known for his innovative spirit, famously fixing a broken headlight for his daughter with duct tape—a solution that humorously lasted over five years.

An individual of remarkable intellect, Leo had a passion for studying theoretical physics encompassing topics such as quantum mechanics, as well as languages like biblical Greek and Spanish. He challenged himself with extreme difficulty Sudoku puzzles and maintained a lifelong dedication to weightlifting. Additionally, Leo was a self-taught pianist, favoring the complex works of composers such as Chopin and Liszt. His pride extended to researching his family’s genealogy back to Poland and undertaking numerous challenging home improvement projects and furniture building.

Leo is survived by his beloved wife, Joanne Dolan Clark, and his cherished daughter, Cindy Clark Wheeler. He took great joy in his grandsons, Joshua, Timothy, and David Wheeler. He is also survived by his step-children, Jean Stacey, Larry Dolan (Karla), Michael Dolan, Annie Dolan, Jeanette Carzon (Michael), Charlie Dolan (Lynne), 4 step-grandchildren, his bonus daughter, Vicki Sanders, and Cindy’s mother, Jeannie Ricigliano.

Leo's legacy is marked by his incredible contributions both in the professional sphere and at home, reflecting a life committed to service, family, and an unyielding pursuit of knowledge. He will be remembered not only for his accomplishments but also for his generosity to his family, his church, and charitable causes that help those in need, especially children and veterans.

A funeral Mass will be celebrated in the Chapel at Sacred Heart Catholic Church in Bowie, MD on Saturday, Sept. 20, 2025 at 12:30 pm. A repast gathering will follow in the church's White Marsh Hall.