Subsurface coal mining is occurring near and underneath Ohio University’s Dysart Woods Land Lab, a 23 hectare old-growth forest. Such mining is associated with changes in groundwater hydrology throughout the region. However, the impacts of these hydrologic changes on forest ecosystems have not been studied. Public controversy over the mining has raised questions for which no answers exist in the peer-reviewed literature. This thesis addresses the question: How much moisture can the soils at Dysart Woods contain- and does groundwater contribute to the site water budget? As a pre-mining observation, volumetric water content of soil was measured in a spatially extensive and temporally intensive manner utilizing a combination of dataloggers, sensors, and hand-held meters in 2005 and 2006. The average soil depth was found to be 1.2 m and the plant-available water holding capacity of the soil was found to be 150mm. Analysis of the stable isotope content of groundwater, precipitation, and xylem water indicated that trees, even in upslope positions, were likely using groundwater during the growing season drought of 2005.