December 18, 2009
This summer the Mattole Restoration Council's Good Roads, Clear Creeks program (GRCC) completed a large project in Panther Creek, a tributary to Mattole Canyon Creek. Mattole Canyon flows into the Mattole River about a mile downstream from Ettersburg and has been one of the tributaries hardest hit by sediment impairments over the last half-century. Panther Creek was targeted for restoration work because in addition to roads crying for improved drainage through culvert upgrades and armored fords, it contained a number of treatable landslides that were contributing extensive sediments to the system and wreaking havoc on the riparian vegetation. With the headwaters of Panther Creek under single ownership, it also boasts a healthy flow of water throughout the late summer months and is home to impressive numbers of steelhead.
When GRCC Director Joel Monschke walked down into Panther Creek for the first time nearly four years ago, he found a steelhead stream clogged with sediments bleeding from nearly twenty landslides perched along a one-mile stream reach. Three things stood out about Panther Creek: first, the sheer number of active slides along such a short stream reach was unprecedented; second, the majority of these slides appeared to be treatable--driven by the creek's erosion at their toe, as opposed to more deep-seated earth flows that are unlikely to be stabilized; and third, an old logging road offered access directly into the heart of the prospective project. What's more, the geology of Panther Creek promised the presence of extensive boulders and maybe even bedrock, a helpful factor when considering the post-restoration adjustments that any stream will experience when it is altered. Here Joel saw an opportunity to stabilize a considerable amount of sediment (more than 50,000 cubic yards) in one relatively small stream reach--meaning that the impacts (always minimized and temporary, yet inevitable) from having heavy equipment in the riparian area would be greatly outweighed by the fact that he could access so many sources of erosion situated nearby.
How does one begin to stabilize a streamside landslide? In the case of one Panther Creek slide, the flow of water in the stream was undercutting the toe of the slide, so Joel realized that the treatment had to address this fundamental factor. Using his knowledge of hydraulic flow and geomorphology, Joel's crew (including his dad, Jack Monschke) re-directed the main channel of the stream away from the base of the slide using a bioengineered riprap wall. This is a fancy term for a large rock structure with live willow planted between the boulders. Additional large rocks, serving as grade-control structures, were added to the bed of the newly constructed channel, and in many places the excavator operator hit large boulders and bedrock which had likely constituted the original channel before logging, floods, and the resultant debris flows drastically altered the landscape 50 years earlier.
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The project was especially rewarding for Jack, who had worked in parts of Panther Creek nearly 20 years earlier trying to accomplish similar goals on a shoestring budget. This time around, funds were available to pay for the importation of more than 100 dump-truck loads of large boulders used to heavily fortify critical streambank zones at the toe of sixteen landslides.
The project was completed just days ahead of the arrival of the first winter storm, and as the last bit of straw was spread near dusk, Joel, Jack and the crew were exhausted. They could almost hear the thundering of water churning down the canyon, ready to test the projects in the months ahead. Only time (and storm intensity) will tell the future of the Panther Creek project, but it was truly a multigenerational effort utilizing experience and innovative techniques to encourage drastic stabilization of an entire landscape.
For more information: www.mattole.org
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TOC for Forest & River News, Winter 2009