Streams like Dry Creek, that experience high flows in the winter, are always moving gravel downstream. A hole dug in times of low flows will be filled back up by the winter’s high flows. This gravel normally comes from upstream tributaries, but in Dry Creek’s case, with the Warm Springs Dam blocking the majority of that gravel flow, the stream bed itself supplies the gravel. As the stream bed is lowered, the bank’s protective cover of tree roots is undermined and the bank, trees and all, collapses, contributing sediment and gravel to this natural conveyor belt.
The first bank robbery was stopped by the courts in the 1970s. A group of landowners upstream of a gravel plant at the West side bridge successfully sued to stop the mining of gravel in Dry Creek. They blamed the loss of their farmland on the instream extraction of gravel, and the court agreed.
The second bank robbery was the result of the Sonoma County Water Agency’s biological opinion that high flows in Dry Creek were negatively impacting the young salmon and steelhead in the stream. They proposed constructing slow water features that would provide refuge for the young fish. To do this, they cut channels through the long gravel bars that are part of the stream bed…