The Aliso San Onofre Watershed covers an area of approximately 362 square miles in southern California. The watershed is primarily urbanized and experiences a Mediterranean climate, with hot, dry summers and cool, wet winters. Precipitation in the watershed is highly variable and influenced by the El Niño-Southern Oscillation (ENSO) climate cycle. The watershed is home to several surface water reservoirs, including Lake Hodges and San Juan Creek Reservoir, which provide drinking water to the surrounding communities. The snowpack in the watershed is minimal due to its proximity to the coast. The hydrology of the watershed is largely influenced by urbanization, with increased impervious surfaces leading to increased runoff and decreased infiltration. The watershed is also impacted by pollution from urban runoff and agricultural sources. Overall, the Aliso San Onofre Watershed faces significant challenges related to managing water resources in an urbanized environment.