Delta panel tries to prepare for sea-level rise

Global warming could put the Sacramento-San Joaquin Delta under much deeper water than previously estimated.

A panel appointed by Gov. Arnold Schwarzenegger is urging him to prepare for a sea level rise of 55 inches in the Delta by the end of this century. That's a lot more water than any estimates currently in use by the state.

The Delta Vision Blue Ribbon Task Force, in fact, found during its research that many state agencies still have no target number at all to plan for sea level rise. That includes Caltrans, which is planning to widen Highway 12, a cross-Delta route between Lodi and Fairfield that already lies 20 feet below sea level in places.

A sea level increase of 55 inches, or about 1.4 meters, would probably overwhelm most levees in the Delta.

It would also likely flood thousands of acres of low-lying urban land surrounding the Delta, including some neighborhoods, urban water intakes, sewage treatment outfalls, highways and other utilities.

"The problem is, this is a high-risk area," said Phil Isenberg, Delta Vision chairman and a former Sacramento mayor and state assemblyman.

"We ought to have a common planning assumption for state agencies. Because the more rise you predict, well, the more complicated life becomes in the future."

The Delta is particularly vulnerable to sea level rise because its towns, farms and infrastructure sit on islands. Many islands have sunk well below sea level due to the loss of peat soils over the past century. They now depend on fragile levees to stay dry.

Scientists advising the Delta Vision panel reported in September that officials should prepare for a sea level rise of 39 inches by 2100. That number was double most estimates in use then.

The task force took that advice and went further in its March 28 letter to the governor.

Citing uncertainty in the projections – and the likelihood that seas will rise more, not less – the panel urged the governor to direct all state agencies to prepare for 16 inches of sea level rise by 2050 and 55 inches by 2100.

"I think that's the high range, but certainly plausible," said Jeffrey Mount, a UC Davis geology professor and chairman of a science panel that advises Delta Vision. "From a planning perspective, that's building in a factor of safety, and that's probably a good thing."

more from the Sacramento Bee