The St. Marys watershed (HUC 04100004) encompasses approximately 1,500 square miles in southeastern Michigan. The watershed is primarily fed by precipitation and snowmelt, which contribute to surface water in the form of streams, rivers, and lakes. The area is known for its heavy snowfall, which can lead to significant snowpack accumulation in the winter months. Surface water in the watershed is primarily used for recreation and hydroelectric power generation. However, the watershed has experienced issues with nutrient pollution, particularly from agricultural runoff, which can lead to harmful algal blooms in reservoirs. Climate trends in the St. Marys watershed have shown an increase in average temperature and a decrease in snowfall over the past several decades, which can impact water availability and quality. Additionally, the watershed has experienced more frequent extreme weather events, such as heavy rainfall and flooding.