A river delta is a landform created by deposition of sediment that is carried by a river as the flow leaves its mouth and enters slower-moving or stagnant water. This occurs where a river enters an ocean, sea, estuary, lake, reservoir, or (more rarely) another river that cannot carry away the supplied sediment.

How is the Delta formed?

A river delta is a landform created by deposition of sediment that is carried by a river as the flow leaves its mouth and enters slower-moving or stagnant water. This occurs where a river enters an ocean, sea, estuary, lake, reservoir, or (more rarely) another river that cannot carry away the supplied sediment.

Where does the Delta water come from?

Fed by runoff from the northern Sierra Nevada and southern Cascades mountain ranges, the Delta is a 700-mile maze of sloughs and waterways surrounding more than 60 leveed tracts and islands.