Blue Slide, Mattole Canyon & Grindstone Creek
As the largest sediment savings project to date, GRCC will stabilize over 300,000 cubic yards of sediment by the end of this project in October 2010. This geographic area of the Mattole watershed has unstable geology and is prone to large landslides. Numerous in-stream large-rock and willow-bioengineered structures have been installed at the toe of major slides along these creeks. These structures are designed to stabilize the stream bank by directing the force of the water away from unstable areas. This work facilitates accelerated growth of streamside vegetation, further stabilizing the riparian corridor and shading the creek. Numerous roads have also been storm-proofed within this large project area.
An undersized culvert on Blue Slide Creek (left) is replaced with a bridge to allow for unimpeded high water flows in the winter. This culvert acted as a velocity barrier during high flows as the creek was forced, at high speed, through the undersized culvert.
In the summer of 2009, GRCC replaced this failing bridge abutment (left) that was leaking toxic creosote into Mattole Canyon Creek with a solid cement foundation that will withstand 100-year floods (right).