Soil properties and forest productivity can be affected during ground-based harvest operations and site preparation. The degree of impact varies widely depending on topographic features and soil properties. Forest managers who understand site-specific limits to ground-based harvesting can alter harvest method or season to limit soil disturbance. To determine the potential areal extent of detrimental (potentially plant growth limiting) soil disturbance based on site characteristics and season of harvest, we developed a predictive model based on soil monitoring data collected from 167 groundbased harvest units. Data collected included dominant site parameters (e.g., slope, aspect, soil texture, and landtype), harvest season, harvest type (intermediate or regeneration), and the machine(s) used during ground-based harvest operations. Aspect (p = 0.0217), slope (p = 0.0738), landtype (p = 0.0002), and the interaction of harvest season x landtype (p = 0.0002) were the key variables controlling the areal extent and magnitude of detrimental soil disturbance. For example, harvesting during non-winter months on gently rolling topography resulted in greater soil disturbance than similar harvest operations on landscapes that are highly dissected. This is likely due to the ease with which equipment can move off designated trails. A geospatially explicit predictive model was developed using general linear model variables found to significantly influence the areal extent of detrimental soil disturbance on nine defined landtypes. This tool provides a framework that, with local calibration, can be used on other forest lands as a decision support tool to geospatially depict landtypes susceptible to detrimental soil disturbance during ground-based harvest operations.