The San Bernard watershed (HUC 12090401) is located in southeastern Texas and covers an area of approximately 1,550 square miles. The hydrology of the watershed is predominantly influenced by the San Bernard River, which is approximately 125 miles long and has a drainage basin of 1,440 square miles. The watershed experiences humid subtropical climate with hot summers and mild winters. Average annual precipitation is around 50 inches, and the heaviest rainfall typically occurs during the summer months. The watershed also experiences occasional flooding, particularly during heavy rainfall events. Surface water in the watershed is primarily used for agriculture and municipal purposes. The reservoirs in the watershed consist of the Lake Texana and the Palmetto Bend Reservoir, which serve as sources of water supply and recreation for the surrounding communities. The watershed is also home to diverse wildlife habitats, including wetlands, forests, and grasslands.