The Rillito Watershed (HUC 15050302) is located in southeastern Arizona, covering an area of approximately 450 square miles. The watershed is characterized by a dry climate, with little rainfall and high temperatures. However, during the winter months, the watershed receives snowfall, which contributes to the surface water and reservoir constituents. The Rillito River, which runs through the watershed, is the primary source of surface water for the area. The hydrology of the watershed is affected by the monsoon season, during which heavy rainfall can cause flash flooding. In recent years, the watershed has experienced a significant decrease in snowpack, which has led to a decline in surface water availability. This trend is expected to continue as the climate in the region becomes even drier. The Rillito Watershed is an interesting area to study due to its unique climatic features and the challenges it faces regarding water management.