Riesel is a city in McLennan County, Texas, United States. The population was 1,062 at the 2020 census, a slight increase from the 1,007 peopl…Riesel is a city in McLennan County, Texas, United States. The population was 1,062 at the 2020 census, a slight increase from the 1,007 people who lived in Riesel at the 2010 census. It is part of the Waco Metropolitan Statistical Area.