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The Prairie Pothole Region (PPR) is defined by a dense network of shallow lakes and wetlands that are fundamental to regional hydrology, aquatic biodiversity, and outdoor recreation. While climate variability dictates the behavior of these systems through snowmelt, infiltration, and "fill-and-spill" dynamics, the specific drivers of streamflow during wet periods remain insufficiently documented. This study utilizes the Cold Region Hydrologic Model (CRHM) to analyze hydrological shifts across select PPR subbasins from Water Year 2001 to 2023. By evaluating key state variables, including Snow Water Equivalent (SWE) and annual evaporation, alongside watershed storage factors like depressional connectivity, we assessed the primary contributors to lake volume fluctuations.Ìý

Our results demonstrate that annual evaporation rates fluctuate significantly, underscoring the heavy influence of year-to-year climate shifts. Spatially, the model reveals a distinct latitudinal gradient, with higher evaporation in the southern PPR than in the north due to elevated temperatures and solar radiation. A longitudinal gradient is also apparent, as more arid western zones experience steeper water losses. Temporally, three hydroclimatic phases were identified: (1) two evaporation-heavy periods (2004-2008 and 2014-2021), and (2) a wet interval (2009-2013) marked by snowmelt-induced flooding and fill-and-spill dynamics. These findings provide a necessary framework for water resource managers to maintain lake health and recreational value in the face of ongoing environmental change.