The Pedernales Watershed (HUC 12090206) covers an area of approximately 818 square miles in Texas. The watershed is characterized by a semi-arid climate with hot summers and mild winters. The hydrology of the watershed is dominated by the Pedernales River, which is a tributary of the Colorado River. The river is fed by several smaller streams and creeks that originate in the hills and valleys of the watershed. The area receives approximately 30 inches of rainfall per year, with most of it occurring during the spring and fall. The watershed is also prone to droughts, which can have significant impacts on the availability of surface water and the health of the ecosystem. The Pedernales River is used for a variety of purposes, including irrigation, recreation, and drinking water supply. The reservoirs in the watershed contain a variety of constituents, including sediment, nutrients, and heavy metals. Interesting climatic facts in the watershed include the occurrence of flash floods, hailstorms, and tornadoes. In recent years, the area has experienced a trend of increasing temperatures and decreasing precipitation, which may have long-term impacts on the watershed's hydrology and ecology.