The discussion of trees or not on the levees has been going on awhile and, putting the safety argument aside for a moment, it is obvious that just from a visual and sanctuary enhancing experience—particularly in the Parkway—trees are a welcome addition.
However, considering the way the levees in our area were built—to narrow the river channels to flush out debris from gold mining—there may be no other option that serves to provide protection from flooding, as well as keeping the levees clear of trees and bushes.
This policy, if it does get implemented, could lead to an opportunity to increase the growth of trees and bushes in the Parkway away from the levees, and the design of more picnic groves and wooden lookouts accessible to the disabled, that won’t add to the weakening of the levee soil.
An excerpt from the article from the Sacramento Bee.
“The levee maintenance policy has never been applied uniformly in California. In fact, local Army Corps officials have worked with the state for years to plant more trees on levees.
“The corps commissioned a scientific peer review of its policy last year. Finished in December, the corps provided The Bee a copy last week.
"The policies and guidance lack scientific foundation, as evidenced by broad anecdotal assumptions and lack of (non-Army Corps) literature citations," the three-member review panel wrote. "The document is from the single perspective that vegetation on levees is bad and should be removed. Some vegetation may help stabilize … levees."
“This echoes the consensus of a science symposium on the subject hosted in 2007 by the Sacramento Area Flood Control Agency. Numerous experts said there was little proof that trees threaten levees. On the contrary, they cited a large body of research that trees may actually strengthen levees by binding loose soils together with their roots.
“The federal policy relies largely on field experience rather than scientific studies to justify its conclusions.
“The corps stands behind its policy and rejects the critique of its scientific merit.
"We don't agree with that at all," said Eric Halpin, Army Corps special assistant on dam and levee safety. "Our primary mission is to keep public safety forefront, and not everyone has that mission. Certainly the folks that are solely focused on the benefits of trees don't have that focus."
