Monday, July 16, 2007

Levee Habitat

If this research proves accurate (was the effect of debris crashing into levee habitat during flooding taken into account?) it could certainly save some money being directed towards habitat removal and retain the beauty of many well habitat populated levees, though there is also a certain, though stark, beauty in the totally grassed levee plan.

A way to save the levee habitat?
A UC Davis study finds plants benefit flood safety
By Matt Weiser - Bee Staff Writer
Published 12:00 am PDT Monday, July 16, 2007

The U.S. Army Corps of Engineers insists that virtually all vegetation be removed from California levees to protect their structural integrity.

But a novel study at UC Davis -- using the largest hydraulic research flume west of the Mississippi -- is bolstering years of scientific findings that show trees and shrubs may actually improve flood safety.

For decades, the corps allowed large vegetation on California levees, in coordination with wildlife agencies, for the sake of habitat. Unlike many other major American rivers, California's big rivers are squeezed into narrow channels, making levees themselves vital habitat for fish, birds, other wildlife and people.

But in February, the corps enforced strict national vegetation guidelines in California for the first time. These rules essentially allow nothing but short grass to grow on levees.

Thirty-two California levee districts were told in February that they failed the standard. More are likely to fail when another inspection occurs this fall, including Sacramento's urban levees.

The corps is updating its national policy but the final outcome is uncertain, forcing levee and wildlife officials into a waiting game. It is unclear if the corps is taking into account the new UC Davis findings.

In the meantime, on June 12, the corps released interim guidance for local levee districts that essentially reinforces existing national policy. Only short grass can grow on the land side of levees. Nothing over two inches tall can grow on the water side.