Dam study had dubious basis

May 25, 2008

Klamath Falls Herald and News Letter to the Editor  

There is an estimated 20 million cubic yards of sediment stored behind the Klamath River dams.

Siskiyou County had a consultant do a preliminary analysis of the studies that had been done. The 2006 Klamath River Dam and Sediment Study was not comprehensive, nor did it detail negative impacts.

In fact, it listed a large group of additional studies that would need to be done. The American Rivers study did not use the accepted engineering model (HEC-RAS) for sediment transport or available detailed topographic reservoir profiles.

The model used accounted for sand-sized sediment, when the majority is silt-sized.     The study is questionable. The studies done by the California State Coastal Conservancy relied on the defective American Rivers study. They failed to take into account that no study had been done on how the flows will carry the sediment.

Dam removal could raise the bed height of the river. (In the recent decommissioning of Marmot dam with 955,000 cubic yards of stored sediment and erosion of 131,000 cubic yards of sediment, the downstream channel rose 13 feet.)

This could inundate adjacent land where there are homes and infrastructure. The fine sediment could also be trapped in gravel spawning beds, requiring a 100-year flood event to return them to a suitable state for salmon.  

A review of sediment bore samples showed some presence of ethylbenzene and creosote compounds. Three bore samples taken in each of the reservoirs indicated that the  sediment contains dioxin. Two samples were above human health standards. (You can read about that toxin and its carcinogenic health impacts at www.ejnet.org/dioxin.

It is likely that the levels of dioxin could kill the “benthic community” or bottom ecology of the river and that a large quantity of floating organic toxic waste particles would pollute the mouth of the estuary.  

Marcia Armstrong

Fort Jones, Calif.

    Editor’s note: The writer is the Siskiyou County fifth district supervisor and represents communities downriver from the dams.

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Source:  http://www.heraldandnews.com/articles/2008/05/25/viewpoints/

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