In this article from the TriValley Herald, the delta pumps, crucial to California’s water supply, are examined in relation to recent fish die-offs.
Here is an excerpt.
Pumps may fuel Delta decline
System supporting fields kills many fish
By Don Thompson, Associated Press
TRACY— Giant pumps in the Sacramento-San Joaquin River Delta are the heart of the state's massive water system, sending water from it where it is most plentiful in Northern California to cities in the south and farm fields in the Central Valley.
Scientists are studying whether the pumps that are so essential to Californians' everyday existence also may be one of the main culprits in an unprecedented die-off of fish species that are considered indicators of the Delta's environmental health.
"This is the lifeblood of billions of dollars worth of agriculture and urban water," said Jeff McCracken, a spokesman for the U.S. Bureau of Reclamation, the agency that operates the federal system.
The state and federal pumps solve a fundamental water imbalance, where 70 percent of river water is north of Sacramento but 80 percent of demand is south of the capital.
But the pumps also lead to a variety of unintended consequences. They kill fish by sucking them in and alter the Delta's natural water flow. Researchers say even changes in the pumping schedule that were intended to benefit fish species may have backfired and are doing more harm than good.
Pumping during winter has increased about 30 percent since 2000. The goal behind changing the schedule was to leave more water in the Delta during spring and summer, when spawning fish were thought to need it most.
Since then, however, scientists have documented a proportional increase in fish being killed through the pumps. Female fish that get sucked into the pumps during winter die before their eggs are fertilized, one possible reason for the perilous decline in Delta smelt.
A similar pattern emerged during the early 1980s when wintertime pumping also was increased, although researchers have yet to prove a link to the decline in fish populations, said Ted Sommer, an environmental specialist with the state Department of Water Resources.
Smelt are driving much of the research into the Delta's decline because they are federally protected. Populations of striped bass, longfin smelt and threadfin shad also are falling.
Scientists fear the fish species' decline is a harbinger of larger environmental problems in California's vast Delta, which provides water for more than two-thirds of the state's residents. The largest estuary on the West Coast, it drains more than 40 percent of the state's land mass and irrigates 4 million acres.
