The Army Corps Relaxes Restrictions for Trees on Levees
American Rivers is often critical of the U.S. Army Corps of Engineers. But last week the Corps released a new interim policy that should allow for better fish and wildlife habitat along levee systems around the nation.
More specifically, the Corps has released an interim policy that at least in theory makes it easier for local levee owners – like counties in the Puget Sound area, where I work – to decide for themselves if they’d like to grow trees on levees while still having a shot a federal funding for levee maintenance and repair. Until this policy change, a levee owner needed clear-cut trees to be eligible for this funding.
This is a pretty wonky issue, but from a river health perspective, it comes down to the fact that trees naturally grow along rivers, where they provide shade (controlling river temperatures), habitat complexity, and food for fish and birds (from bugs on the trees). We’d like to see fewer levees where possible, but where levees already exist, trees on levees are better than no trees when it comes to fish and wildlife habitat.
From an engineering perspective, there is increasing evidence that trees often help stabilize levees — their roots can act like rebar – and only rarely pose a risk to levee integrity. Some levee owners, like King County, Washington, have actually engineered trees into levees to make them stronger and better protect communities and infrastructure from flood damage.
The new Corps policy will help levee owners in Puget Sound, the Sacramento River basin, and other river basins, get out from under a conflicting federal mandate where one federal agency (like the National Marine Fisheries Service or Fish and Wildlife Service) says levee owners need to manage levees to improve habitat for threatened fish and birds, while the Corps says all trees –of any size – need to go.
There are still questions and concerns about whether the Corps’ new policy will be made permanent and if it will be implemented at the local level to provide local levee managers with the flexibility they need to measurably improve habitat and protect the public from flood damage. But the Corps is moving in the right direction on the levee vegetation issue, and we applaud them for it.