The Upper Trinity Watershed (HUC 12030105) is located in northern Texas and covers an area of approximately 2,875 square miles. The watershed is characterized by a humid subtropical climate with hot summers and mild winters. The hydrology of the watershed is heavily influenced by the Trinity River, which flows through the region and provides surface water for both drinking and irrigation. The specific snowpack in the watershed is limited due to the mild winter temperatures, with most precipitation falling as rain. Reservoirs within the watershed include Lewisville Lake, Grapevine Lake, and Ray Roberts Lake, which provide water for the Dallas-Fort Worth metroplex. Interesting climatic facts include the high frequency of severe thunderstorms and occasional tornadoes in the spring and early summer months. In recent years, the region has experienced a trend towards warmer temperatures and more frequent drought conditions.