It provides the necessary fluid head (potential energy) for the California Aqueduct to flow for approximately 80 miles (130 km) south past the O'Neill Forebay and the San Luis Reservoir to the Dos Amigos Pumping Plant.
[2] In dry years, water pumped from the Delta creates a hazard to spring-run salmon.
As the Banks Pumping Plant pulls water from the Sacramento River southward across the Delta, it disrupts the normal flow direction of east to west that salmon smolt follow to the Pacific Ocean.
Populations of salmon and steelhead trout have reached critically low levels in the decades after SWP water withdrawals began.
The fish migration issue has become hotly contested in recent years, with rising support for the construction of the Peripheral Canal, which would divert water around the Delta, restoring the natural flow direction.