Army Corps of Engineers Plans to Cut Down All Trees Near Levees

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.

US Army Corps of Engineers to cut down trees along levees

US Army Corps of Engineers to cut down trees along levees

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.

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Author: Jennifer Lance

Comments
  1. Are they crazy? Don’t they realize that trees strengthen the shores and keep soil from eroding? If they cut down those trees, they will be facing an even worse disaster the next time a levee breaks!

  2. Sure the trees may strengthen the levee when the roots are alive, but when the tree dies and the roots decompose, there will be an underground network of holes in the levees.

    I know it’s easy to hate on the Corps especially when they are getting PR like this, but maybe sometimes it’s better to be safe than sorry. I’m sure they have a proper reason for doing this

  3. I’d bet my house that the army corps or engineers has thought about whether the tree root systems are strengthening the levees or not. Let us remember that tree root systems can also help to break down firm rock and soil not just prevent erosion of loose dirt. Erosion is probably not the primary concern of a levee considering that they are for the most part well maintained pieces of infrastructure.

  4. wish someone would have told them this before they came through my backyard in munster, indiana. no more trees. : (

  5. Who zoned these low-lying areas as suitable for people to live and work in? Why are citizens paying federal taxes to protect local communities of stubborn people who choose to live in these places where real estate prices are low . . . because they’re flood prone areas? I feel like I’m taking crazy pills thinking about this.

  6. As much as I dislike the corps ( I work alongside them alot), they are correct on this. Tree roots can severely impact the integrity of a levee or dam. Roots that penetrate to the containment side are an obvious hazard. Another is trees dont live forever, once a tree rooted into a leveee dies and the roots decay, well that should be obvious too.

  7. Luke is right. Tree roots hold soil together while alive, but when they die, they first dry out and shrink, allowing water and air to penetrate further into the soil. Then they rot, leaving tunnels in the soil behind. But that’s not the biggest issue. The biggest issue is one of soil compression.

    Compression in a levee or dike can and should exceed several thousand pounds per square foot. Tree roots that penetrate soil actually break it up in the process, decreasing the soil compression. This is why forest floors are so fertile – the tree roots are constantly breaking up the lower layers of the soil to allow air, water and organisms to penetrate and thrive, which makes for a great peaty loam to grow stuff in. Dikes and levees though use rammed and compacted earth, and sometimes concrete where economical, and have to be as densely packed as possible to prevent water migration and seepage.

    Trust me – as a part time horticulturalist, the Corps know their stuff on this count.

  8. Pingback: Live Oak Levees in Louisiana « Quinta Scott’s Weblog

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