The San Diego Watershed (HUC 18070304) covers an area of approximately 1,757 square miles and is located in Southern California. The watershed is characterized by a semi-arid climate with most of the precipitation falling during the winter months. The hydrology of the watershed is dominated by the San Diego River, which begins in the Cuyamaca Mountains and flows westward towards the Pacific Ocean. The watershed also includes several significant reservoirs, including Lake Hodges and El Capitan Reservoir. Snowpack is generally not a significant contributor to the watershed's water supply, as the region rarely experiences significant snowfall. Surface water is primarily sourced from the San Diego River and its tributaries. The reservoirs in the watershed are primarily used for water storage and recreation. Interesting climatic facts and trends include an increase in average temperature over the past century and a decrease in precipitation in recent years. The region is also vulnerable to wildfires, which can have significant impacts on the watershed's hydrology and water quality.