category

California Sacramento Delta islands are sinking

subsidence-diagram

As if California didn’t already have enough water worries. Water flows down from the Sierras to the Sacramento Delta, and then much of it goes to southern California. The delta is the most crucial water supply in California. Delta islands and surrounding areas contain immensely fertile farmland as well as cities. The problem is, they are generally lower than the water level in the Delta, protected by levees. The levees are old and the islands are sinking. If levees fail, it would be a catastrophe for residents and imperil southern California water supplies.

Delta farmers say, ‘We take good care of our levees.’ I understand their point. They have made heroic efforts. The simple fact is there have been 144 levee failures. There have not been many lately. We have not had high inflows, high winds and high tides. But it’s almost akin to saying it’s been a long time since an earthquake.” According to Mount, risks in the Delta are high because “there are multiple potential causes.” Then he reels them off: overtopping, seepage, under-seepage, quakes. Ah, and rodents.

Every island that fails will subtract huge amounts of Sierra stream flow that might otherwise go into reservoir storage.

Trust of Southern Californians, however, is as rare as hens’ teeth in these parts. Having identified me as a reporter from Los Angeles, Miller says accusingly, “What bothers me is they [scientists and policy-makers] worry about if the Delta is flooded then you won’t have clean drinking water. If the Delta is flooded, we’ll drown!”

There are no easy answers here. Upgrading levees is expensive and may not even completely solve the problem.

Comments are closed.

Powered by WordPress. Designed by WooThemes