Mannshardt is from
Yuba City, California, and was the 1995 valedictorian of
Yuba City High School. She majored in mathematics at
Sonoma State University, and did graduate study in statistics at the
University of North Carolina at Chapel Hill, earning a master's degree in 2005 and completing her PhD in 2008. Her dissertation,
Asymptotic Multivariate Kriging Using Estimated Parameters with Bayesian Prediction Methods for Non-Linear Predictands, was supervised by Richard L. Smith. Her research focused on
climate change and extremes in climate and weather. While a doctoral student, Mannshardt was also a research fellow at the
National Oceanic and Atmospheric Administration. She became a postdoctoral researcher at the
Statistical and Applied Mathematical Sciences Institute, working with Peter F. Craigmile, and a visiting assistant professor at
Duke University before becoming a government statistician at the EPA. Mannshardt was the associate director then acting Director of the Information Access and Analytic Services Division at the
United States Environmental Protection Agency. Mannshardt served as the director of the Statistics Methods and Innovation Program at the National Center for Science and Engineering Statistics at the National Science Foundation (2022–2024). Mannshardt chaired the Government Statistics Section of the
American Statistical Association (ASA) in 2019. She is the 2022 chair of the ASA Section on Statistics and the Environment and currently serves as the Vice Chair of ASA's Membership Council (2023-) ==Recognition==