The pile dike structures are very old and have increasingly deteriorated, damaged by high flows. A structural and functional assessment of the Columbia River pile dikes in 2011 determined that 100 pile dikes are in poor structural condition; nearly 80 pile dikes are missing king pile safety markers.
Repairing missing safety markers is the first priority for pile dike maintenance. While this need is critical, pile dike maintenance hasn't been funded in recent years. Instead of waiting for increased funding, we're seeking ideas to lower repair costs and repair pile dikes in phases. We're partnered with the U.S. Coast Guard and boating safety groups to improve safe navigation around pile dikes and increase public awareness.
After the king piles are repaired, major maintenance studies and design reports will prepare for major maintenance to restore pile dike functions. The 2011 assessment prioritized pile dike systems for repairs in phases.
An interesting finding from the 2011 assessment was how many pile dikes actively help create and/or protect shallow water habitat, which benefits juvenile salmon. But without major maintenance repairs, pile dikes' navigation functions and shallow water habitats are at risk.
The Corps is currently studying the relationship between pile dikes and shallow water habitat, and recognizes opportunities to combine efforts and resources between navigation and juvenile salmonid recovery. Further research may help us better understand how juvenile salmonids interact with different pile dikes and adjacent habitats.
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