California has a diverse hydrological system with major surface flows, including the Sacramento and San Joaquin River systems, which provide water to the agricultural heartland. The state has numerous reservoirs and dams, including the Oroville Dam, which is the tallest in the US. California's climate is characterized by long periods of drought, punctuated by occasional heavy rainfall events. The state's hydrology is heavily influenced by snowpack, which accumulates in the Sierra Nevada mountains during the winter and provides a critical source of water during the dry season. The state's watersheds are also important, with the Sacramento River being the largest, providing water to much of Northern California. Overall, California's water management is complex and requires careful planning to balance the competing demands of agriculture, urban areas, and the environment.