April 5, 2006
Watershed and fisheries restoration is part science, part art, part engineering, and part sociology. Ancestor Creek is just one of the more than twenty tributaries to the Mattole River headwaters where Sanctuary Forest and its partners are working to restore the habitat of endangered salmon as part of the Upper Mattole Watershed Rehabilitation Project. Many of the successes and lessons learned from this project are seen in Ancestor Creek.
Sanctuary Forest initiated the Upper Mattole Watershed Rehabilitation Project in 2000 with the goal of decommissioning or upgrading all roads and related sediment pollution sites on the nine square miles of conserved lands within the Upper Mattole River and Forest Cooperative. Expecting an enthusiastic reception at our first public meeting announcing Sanctuary Forest's intention to undertake large-scale watershed restoration work, we were instead met with great skepticism by a significant segment of the community.
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As result of the concerns expressed, Sanctuary Forest promised the community we would provide tours of the restoration sites so people could see the erosion problems themselves. We also committed to undertake a rigorous monitoring program, and to report on the effectiveness of the restoration work after the first season.
We began holding tours in Ancestor Creek because it was easily accessible by an existing hiking trail. There we took walks in the rain with the community and observed together how improperly drained roads diverted streams. We stood on a fill-crossing where nine feet of sediment buried the creek; we saw the eroding banks of a stream crossing where laborious hand efforts had taken days to dig a tiny, narrow channel to improve fish passage. As people began to better understand stream hydrology and erosion, they could realize that it would take the same equipment used to build roads to repair the damage caused by them.
Sanctuary Forest called on the community to help fulfill its pledge of a rigorous restoration monitoring program by asking people to volunteer as monitors. Volunteers undertook four kinds of monitoring: on-site turbidity sampling, off-site turbidity sampling, cavity measurements, and qualitative observations. Overall the monitoring after the first year showed that sites excavated by Sanctuary Forest had very low post-treatment erosion: an average of 14% of the total calculated sediment savings. But we also had three significant site failures.
We learned from these failures and incorporated the lessons into our work the following year. Two of the sites that failed were in low-gradient stream reaches. These sites experienced significant head cutting through sediments that accumulated behind the stream crossing. Ancestor Creek was also at risk for this same kind of problem because it is low-gradient. To prevent this problem a large grade-control structure was installed to prevent erosion from moving upstream after removal of the fill crossings in Ancestor Creek. This was highly effective, and similar structures are now used in all low-gradient streams where crossing removals are involved.
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Volunteers have been taking turbidity samples near the mouth of Ancestor Creek during major storms since the winter of 2002-2003. At the same time samples have been taken from nearby McNasty Creek. These two creeks have watersheds very similar in size and are otherwise comparable except that Ancestor Creek had restoration work and McNasty Creek has not been treated for sediment pollution. In the first winter post-treatment, the treated stream, Ancestor Creek, generally showed higher turbidities than McNasty Creek, indicating a greater load of sediment. However, in the second and third winters, post-treatment, Ancestor Creek has generally shown much lower turbidities than the untreated McNasty Creek. It has taken many years to collect, but this data demonstrates the overall effectiveness of road removal and upgrade work in reducing sediment pollution.
The lessons learned from Ancestor Creek have played a big part in the overall success of the Upper Mattole Watershed Rehabilitation Project. The project is now in its second and final phase, which expanded to incorporate the remaining nineteen square miles of industrial and rural residential lands within the twenty-eight square miles of the Mattole River headwaters. There are now thirty-eight federal, state, private, conservation and industrial landowners participating who have given permission for implementation of projects on their land to benefit fisheries. Project partners have raised more than $2 million in state, federal, and foundation funds to implement the work, with major grants coming from California's Department of Fish and Game, Coastal Conservancy, Wildlife Conservation Board, and State Water Resources Control Board. Project implementation is scheduled to be completed in 2007, with monitoring to occur through 2015.
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TOC for Forest & River News, Spring 2006