A delta levee that burst in 2004 is leaking again, though officials differ on whether to call it an emergency.
The levee on Upper Jones Tract in San Joaquin County burst along Middle River, just north of Highway 4, on June 3, 2004. It flooded the 2,000-acre tract and 2,000 more acres on adjoining Lower Jones Tract.
The repair apparently began leaking at an unusually fast rate several months ago. That prompted officials at Reclamation District 2039, which maintains levees on the tract, to declare an emergency.
Dante Nomellini, a Stockton attorney for the neighboring district on Lower Jones Tract, said the leakage qualifies as an emergency. The two districts are linked by a railroad underpass and both would flood if the levee broke.
The state Department of Water Resources, however, has not decided whether to declare the leak an emergency. It said the situation requires monitoring, although it has granted money to start repair work.
The Jones Tract leak underscores the tricky business of fixing delta levees, a vast network of barriers at risk because many are old and considered not strong enough to defend against severe floods.
The 2004 break in the Jones Tract levee highlights the threats to delta levees: It occurred on a sunny day, not in a storm, and officials eventually blamed either a porous foundation or rodent burrowing.
Two-thirds of California residents and millions of acres of farmland depend on delta water. Levees in the estuary protect that freshwater supply from contamination by salty tides. Another levee break on Jones Tract could draw a surge of saltwater into the estuary and require water deliveries to be halted.
Leaks are common at many levees in the Sacramento-San Joaquin Delta because they are built from poorly engineered soils atop uncertain foundations.
Mike Mirmazaheri, delta levee program manager for the DWR, said it's not unusual for seepage at a repair site to worsen over time.
$350,000 granted for a fix
Repaired levees in the delta are especially prone to leakage because the fix usually must be performed underwater.
On Upper Jones Tract, the 2004 break was closed by filling the bottom of the void with large rocks, then adding smaller rocks and dirt on top.
As the material settles, Mirmazaheri said, it sometimes leaves voids within the levee that increase seepage.
To plug the Jones Tract leak, DWR granted the levee district $50,000 to design a fix and $300,000 more to subsidize construction.
But it wants the district to first commit to repair any environmental damage caused by the work, which requires an agreement with the U.S. Army Corps of Engineers.
It also wants the district to monitor the rate of seepage and slumping in the levee itself to determine the severity of the problem.
Mirmazaheri said there is little risk of a sudden failure.
"If it continues seeping through, and if it continues settling, then it could potentially fail in the future," he said. "When or how soon, these are questions we don't really have an answer to.
"That's why monitoring becomes important."
Nomellini said water leaking through the Jones Tract levee is not cloudy or muddy, a classic danger sign that the levee is eroding from within.
"This isn't normal leakage. It's no time to fool around," Nomellini said.