Ecohydrologic controls on the critical zone are strongly influenced by Eastern hemlock (Tsuga canadensis), a foundation tree species established throughout much of Eastern North America. Eastern hemlock populations are currently threatened by the hemlock woolly adelgid (Adelges tsugae), an invasive insect. Hemlock woolly adelgid populations have been expanding rapidly throughout the native Eastern hemlock range. Given the complex relationships between canopy interception, unsaturated and saturated groundwater storage, and root water uptake, it is not immediately clear how Eastern hemlock loss will affect the hydrologic cycle. This research presents a review of past studies on this theme, and then investigates the hydrologic impact of Eastern hemlock mortality across a regional sample of catchments utilizing simulation and statistical modeling approaches. Modeling outcomes suggest that Eastern hemlock mortality will augment flooding potential. Finally, summaries of future studies examining Eastern hemlock plant hydraulics and control of fluvial flooding are presented.