The Army Corps of Engineers has decided all trees must be removed that are 15 feet from a levee. The corps is worried tree roots could weaken levees meant to protect low elevation communities. Of course, the corps’ record is marred with mistakes when it comes to safeguarding communities from catastrophic floods, like New Orleans.
Ironic the corps wants to remove trees when vegetation is often credited with streambank stabilization. According to the state of Maine’s document on erosion and sediment control:
Stands of full-grown trees protect streambanks from erosion through the binding of soil with their roots. Shrubs provide even better erosion protection, and riverside stands of willow trees are often replaced naturally by colonies of shrub-like willows. These plants hold the soil with their root systems and reduce water velocities. They also protect tree trunks from damage caused by breaking ice and help to prevent the formation of strong eddies around large trees during flood flows. Shrub vegetation is particularly beneficial along the impact bank of a stream meander, where maximum scouring tends to occur.
Already thousands of trees have been cut down, and there are over 100,000 miles of levees in the US. Environmentalists, conservationists, and local citizens are protesting the corps’ tree removal program. The Associated Press explains:
“The literature on the presence of vegetation indicates that it may actually strengthen a levee,” said Andrew Levesque, senior engineer for King County, Wash., where the corps wants trees removed on the six rivers considered vital to salmon populations. The anti-tree policy arose from criticism directed at the corps after Katrina breached levees in New Orleans in 2005…”The corps’ new edict was regarded as a major change in policy,” said Ronald Stork, senior policy expert with California Friends of the River in Sacramento. “Something that is cheap and inexpensive is a chain saw. It was something to do that didn’t cost a lot of money that made you feel better.”
Independent experts agree a tree has never caused a levee to fail. George Sills, former member of the corps’ Engineer Research and Development Center states, “There’s never been a documented problem with a tree,” including in New Orleans.
Some local residents in Louisiana have been able to save trees in historic areas from corps removal, as well as wildlife officials in California have been able to protect habitat along levees. The removal of trees along levees is not based on empirical scientific evidence, but tree eradication may make levees easier to inspect for safety. Whether it is to make levees stronger or make them easier to inspect, the Army Corps of Engineers tree removal program has come under heavy criticism.