West Tyson County Park is a 673-acre park in St. Louis County, Missouri, east of Eureka, bordered by the Meramec River and neighboring park and research lands. Its ground was once part of the Tyson Valley Powder Plant during World War II. St. Louis County began assembling the park with 210 acres acquired in 1955 and another 410 acres added in 1979. Later development balanced recreation with environmental restoration, including creation of the Chubb Trail in 1985 and the William Epstein Memorial Prairie project in 1988. Today it forms part of the county park system as a regional park shaped by both wartime industry and conservation.