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Summer No Vacation for Smelt
Nature, California's relentless thirst and human error conspired to make the early summer of 1999 a particularly deadly one for Delta smelt, creating a textbook example of the hazards facing efforts to protect wildlife and simultaneously supply water to farms and cities.
Cal Fish & Game scientists are reviewing their data, trying to find out why so many of the threatened fish lingered for so long within reach of the state and federal pumps in May, June and July, leading to high entrainment levels and a month-long slowdown at the pumps that had water officials and farmers biting their nails and environmentalists calling for a complete shutdown.
According to Fish & Game's Heather McIntire, there have been large takes at the pumps before, although they usually occurred in dry years, when the smelt's spawning habitat in fresh water areas of the Estuary is limited to the Delta and upstream areas. "They may have stayed because the Delta water was cooler than normal this year, or their preferred food was more abundant here," she says.
The pumps hit the take limit in late May, leading U.S. Fish & Wildlife to restrict pumping to less than 3,500 cfs (from the usual 6,000 to 8,000 cfs). As a result of the cutbacks San Luis Reservoir, where heavy spring flows would normally have been stockpiled during this period, had to be drawn down to supply San Joaquin Valley farmers and Silicon Valley industries, raising the specter of water shortages later this summer. And despite the cutbacks, "more than six times the legal allowable take was entrained at the facilities in May and June, and twice the legal take in July," says McIntire.
In late June, as calls from water users grew increasingly frantic, "the smelt began moving away in the right direction," says U.S. Fish & Wildlife's Pat Foulk, and the agency granted permission to ramp up pumping. But a clean getaway for the little fish was not in the cards: three weeks later wildlife agencies discovered that a temporary barrier at Grant Line, required by permit to remain open while Delta smelt salvage is high, had been inadvertently closed. With the barrier closed, explains McIntire "the hydrodynamics of the south Delta reverse direction and pull fish toward the pumps from Turner and Columbia cuts." McIntire says the specific impact of the barrier closure is unknown, as is the overall effect of the summer's events on the total smelt population.
Contact: Heather McIntire at (209)948.7087.
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