The Delta area discharges over 40% of the state's total runoff into San Francisco Bay. It is the low point of the Sacramento-San Joaquin Valley of which water flows before going to the ocean. Because of its geographical position, the Delta serves as the collection point for much of the states runoff which results in the majority of the water supple to Northern California. It is through the channels of the Delta that this water must pass to satisfy the needs of the Delta, the agricultural lands of the San Joaquin Valley, the San Francisco Bay area and the densely populated southlands.
The Delta was once a huge marsh formed by the confluence of several large rivers, including the Sacramento and the San Joaquin. While the early growth and development of the Delta was steady, the discovery of gold in California made a dramatic impact on the Delta region.
There was no private ownership of land in the Delta until the State authorized sale of these marsh lands for one dollar an acre in 1861. When control of the region was given to counties, levee construction became widespread as a way to reclaim land for farming. Man-made elevated riverbanks, called levees, hold back the water from the lands that are farmed. These levees have created approximately 60 islands in the Delta. The rich peat soil of many of the islands provides impressive harvests of such crops as asparagus, tomatoes, corn and pears.