Delta smelt, that tiny ecological bellwether fish, is warning California water officials to turn off, or at least turn down, the Tracy pumps. The Delta smelt, which in 1993 was first listed as a threatened species when its population had fallen by an estimated 90 percent, is endangered.

For the past several years, the numbers of this open-water fish that has a year’s life expectancy have fallen drastically. Biologists, environmentalists and a few politicians are blaming the demise on state and federal pumps that reverse the flow in the south Delta while they suck water from the Clifton Court Forebay, northwest of Tracy, and end send it south in concrete-lined canals.

For 10 days this spring, the state pumps were turned off before operating at 10 percent of normal to protect what’s left of the smelt population. It’s fortunate this ecological crisis is occurring in 2007 and not next year. There is enough water in the reservoirs to feed that thirsty beast — the Metropolitan Water District of Southern California. But under similar conditions, another extremely dry year would jeopardize this critical water source.

There should not be any chaos in Sacramento, since the Delta smelt experienced a similar situation 14 years ago. That led state water regulators to reduce the pumping and forced discussions by state and federal agencies, water users and environmentalists that culminated in California’s most ambitious water plan, Cal-Fed. It also became the state’s most failed and wasteful water plan.

In 2005, the state water regulators released a 14-point, science-based framework to address a new decline in Delta smelt. It came three years after scientists proclaimed a dramatic renewal of the smelt population. Under the Delta Smelt Action Plan, $25.4 million is spent annually on studies and efforts to counteract the latest fish decline. But that’s only the tip of the looming monetary iceberg. There are proposals to spend $75 million on permanent gates to dam water each spring in parts of the south Delta, $30 million to grow plankton, $11.5 million to restore the Suisun Marsh and $7 million to replace each fish screen on the giant water pumps. That’s not counting the 800,000 to 1 million acre-feet of fresh water that will have to be designated for the Delta to maintain the smelt’s habitat.

Since 2005, the state Resources Agency has developed the Pelagic Fish Action Plan that calls for limiting upstream flows in Old and Middle rivers in the winter, maintaining downstream flows in Old and Middle rivers in the spring and exclusion of south Delta barriers until June 1, plus $75 million worth of additional habitat improvements.

All these recommendations and projects and their potential costs should be weighed when state and federal officials discuss the immense and comprehensive plan necessary to save the Delta and to continue to provide quality water to Tracy residents and 25 million other Californians and 5 million acres of farmland.

Saving the Delta smelt and quenching California’s thirst won’t be cheap.