Friday, January 30, 2009

Levees, Trees & Dams

This story in the Bee that hundreds of trees will be lost along the river is a very sad one as their welcoming shade provides a pleasant place to cast a line or just watch the water go by.

Unfortunately, the reliance on levees for flood control, rather than dams, requires their removal, and that is a real shame.

There is a solution—that would obviously have to wait until funds are available—that would solve the water problems for the larger region and that is the raising of Shasta Dam to its originally engineered height of 200 feet higher than it now is, tripling its water supply, which an 2004 article from the Los Angeles Times describes.

An excerpt.

‘….From an engineering standpoint, it's a piece of cake. The dam, built between 1938 and 1945, was originally planned to be 200 feet taller. At 800 feet, it would have been the highest and biggest in the world.

“Sheri Harral, public affairs officer at the dam, said World War II and materials shortages associated with the war effort led to a decision to stop construction at 602 feet.

"The thinking was to come back and add on to it if ever there was a need to," Harral said. "They started looking at raising it in 1978."

“If Shasta Dam had been built up to its engineering limit in 1945, it is arguable that Northern and Central California would not be facing a critical water shortage now.

“According to a 1999 Bureau of Reclamation study, a dam 200 feet taller would be able to triple storage to 13.89 million acre-feet of water.”

An excerpt from the Sacramento Bee article.

“Sacramentans soon will understand just how massive the region's biggest modern levee project is as workers this week begin removing 900 trees to make way for construction along the Sacramento River.

“About 800 of those trees are native oaks – mostly valley oaks – including some more than 60 inches in diameter.

“They may come to symbolize the tightrope that California walks between flood safety and habitat protection.

“The trees must go because they're in the footprint of a $619 million project to build giant new levees encircling the Natomas Basin. The project was required by a 2006 U.S. Army Corps ruling that existing levees don't adequately protect the basin's 70,000 residents.

“The Sacramento Area Flood Control Agency designed new levees up to 300 feet wider to accommodate another Army Corps rule that forbids trees and structures on levees.”