The Delicate Act of Juggling Water

The scene is part of a complicated choreography of water releases underway in the San Joaquin River Basin as dam managers try to avert serious flooding in this sodden spring of endless rain and monster snowpacks in Northern and Central California.

Here, 20 miles northeast of Fresno, dam operators have to make room for the coming snowmelt in the smallest reservoir in the big federal water project that greens the Central Valley. But they can't let out too much water or it will break through the aging, earthen levee system that guards towns and farms downstream.

It is a season of round-the-clock monitoring, canceled vacations and anxious weather readings. "At times like that my body is running at 100 miles an hour," said Friant operations chief Tony Buelna, who at the beginning of the month, when nature was filling the reservoir to the brim, got a total of four hours of sleep in three days.

With last week's weather drier than expected, Millerton's levels were starting to fall and Buelna was getting some sleep. But the potential for disaster will last well into the summer.

In the High Sierra, where the headwaters of the San Joaquin arise southeast of Yosemite National Park, the snowpack is 170% of the norm -- 50 feet deep in some places. When that melts, there will be enough runoff to fill Millerton four times over.

The 319-foot-tall Friant Dam, built at the beginning of World War II and the only one on the main stem of the San Joaquin, is one of nearly a dozen in the drainage basin. There are 10 others on the river's tributaries, which branch out like vines on a trellis as the San Joaquin runs northwest to its delta just east of San Francisco Bay.

Each of those dams is spitting water into the system from swollen reservoirs, complicating the release calculations. The dam operators are like air traffic controllers, constantly juggling what is coming in and out of their reservoirs. But unlike air controllers, they have little say over what comes in -- and they have to be aware of what every other dam is doing.

With much of the state on flood alert and an emergency declaration in more than a dozen Northern and Central California counties, dam managers consult with each in daily teleconferences. They listen to morning weather briefings and pore over computer models that try to predict runoff based on the temperature, precipitation and snowpack.