Here's why levee trees must go

Recently, questions have been raised about the number of trees being cut down as part of a levee restoration project along both sides of Rosenberry Drive (commonly known as Dike Road) on the North Idaho College campus.

To conform with levee recertification regulations imposed by the Federal Emergency Management Agency (FEMA), the Army Corps of Engineers is requiring the removal of some trees. Trees are a major concern along levees because they can severely weaken the integrity of the flood protection embankment in the event of a major flood or storm.

Should the levee not receive FEMA certification, property owners in that area - NIC, Fort Grounds and surrounding neighborhoods - would be required to purchase costly flood insurance.

The city's No. 1 goal with this project is to recertify the levee while keeping as many trees as possible. It's important to remember that the Army Corps of Engineers initially mandated removal of all the trees along the levee. Thankfully, the city was able to negotiate with the Army Corps of Engineers and the agency subsequently changed its policy, allowing many trees to remain.

There were a number of components involved in the analysis for determining trees to be removed from the levee. Many professionals were involved in this process, including technical contributions from a certified arborist, civil engineers, geotechnical engineers, and numerous discussions with the city of Coeur d'Alene and the Army Corps of Engineers.

Tree removal decisions were carefully made, balancing the desire to retain as many trees as possible while mitigating risks to the structural stability of the levee. Below is a generalized summary of what necessitated tree removal.

* A tree health assessment was performed by a certified arborist on the trees in proximity and on the levee. Trees found to pose a risk due to health concerns were identified for removal.

* Trees located within specific zones on both sides of the levee with roots intersecting the core levee were identified for removal because it was determined these roots could potentially jeopardize the structural integrity of the levee in the event of toppled trees.

* Trees with root penetration that posed the potential to create seepage, weakening the ground around them, were identified for removal. These forces jeopardize the structural integrity of the levee.

* To perform the slope restoration, trees were identified for removal to accommodate construction efforts. If the tree were to be partially buried due to slope restoration, it had to be removed as it would not live due to the burial of some of the trunk.

The bottom line is that the city wishes to preserve as many trees as possible, but the long-term stability of the levee as determined by the city's consultant will continue to be the chief criteria regarding tree removal and levee recertification. Many professionals were involved in establishing a plan for levee maintenance and the city continues to follow that plan.

And finally, the city is pleased that the tree removal process was performed by city staff, saving a significant amount of money, a portion of which can be used for public amenities along the levee.

Keith Erickson is a former newspaper reporter who now serves as communications coordinator for the city of Coeur d'Alene.