<P> California's interconnected water system serves over 30 million people and irrigates over 5,680,000 acres (2,300,000 ha) of farmland . As the world's largest, most productive, and most controversial water system, it manages over 40,000,000 acre feet (49 km) of water per year . </P> <P> Water and water rights are among the state's divisive political issues . Due to the lack of reliable dry season rainfall, water is limited in the most populous U.S. state . An ongoing debate is whether the state should increase the redistribution of water to its large agricultural and urban sectors, or increase conservation and preserve the natural ecosystems of the water sources . </P> <P> California's limited water supply comes from two main sources: surface water, or water that travels or gathers on the ground, like rivers, streams, and lakes; and groundwater, which is water that is pumped out from the ground . California has also begun producing a small amount of desalinated water, water that was once sea water, but has been purified . </P> <Table> <Tr> <Td> </Td> <Td> This section's factual accuracy may be compromised due to out - of - date information . Please update this article to reflect recent events or newly available information . (August 2017) </Td> </Tr> </Table>

Where does most of california's water come from