By Jessica May:
Our Journey Begins
11/15/19 – On an overcast morning, the Restoration Ecology students piled into two vans and set out to visit salmonid restoration sites at Lagunitas Creek in Marin County. Our first stop was a campground parking lot, where we met a few of our tour guides for the day: Sarah Phillips, a former Sonoma State ENSP student who is now the Urban Streams Program Manager at Marin County Resource Conservation District; Erik Young, the President of the North Bay Chapter of Trout Unlimited; and Teddy Hanford, a project estimator at Hanford Applied Restoration and Conservation. After a brief meet-and-greet, our expert guides gave an overview of the history of the Lagunitas Creek watershed and the threatened and endangered salmonids that are native to it.
They explained how the biggest threats to salmonids are overharvesting, competition with hatchery fishes, impacts from hydropower dams, and habitat reduction and degradation (collectively known as the “4 H’s”). The Coho salmon (Oncorhynchus kisutch) in Lagunitas Creek comprise approximately 20% of the endangered Central Coast Coho ESU (evolutionarily significant unit). These Coho are most impacted by the presence of several dams which reduce access to upstream habitat and alter conditions downstream. Since the addition of fish passage and/or the removal of the dams is infeasible, restoration efforts are focused on enhancing the habitat area downstream of the dams. Today, we are visiting three restoration sites in various stages of successional recovery.
Floodplain Restoration
We walked up the road to the first site where we met Preston Brown, the Conservation Director for the Turtle Island Restoration Network and watershed biologist for the Salmon Protection and Watershed Network (SPAWN). This site was designed by SPAWN and construction was finished just a few weeks ago by Hanford ARC. Preston explained how they removed several abandoned structures and excavated the areas surrounding the channel to restore the historic floodplain.
Living willows were strategically placed in the channel to slow the water movement and reduce erosion while creating sinuosity and complexity. Branch mattresses and willow waddles were installed to stabilize the banks and reduce erosion. Sarah emphasized that while erosion is a natural process, fine sediments can smother salmonid eggs so erosion should be minimized near Coho spawning grounds. Teddy pointed out the best management practices (BMPs) that were used during installation such as biodegradable coir erosion fabrics and waddles, living willow stakes, and that all large woody debris installations were sourced on-site. In addition to excavating a secondary channel, lowering the floodplain, planting living willows instream, installing bank stabilization fabric, and creating habitat for California freshwater shrimp (Syncaris pacifica), efforts were made to eradicate Fallopia japonica (a noxious weed known as Japanese knotweed).
Increasing Channel Complexity
After visiting the newly constructed SPAWN restoration site, we drove a few minutes up the road to Turtle Island’s office, where Preston showed us their on-site native plant nursery and another restoration site that was completed last year. This site was restored to add channels with varying depths that would be able to accommodate a variety of water flows. Hanford ARC also implemented this project and Teddy explained how they used adaptive management to clear out clogged channels and make alterations after the first rainy season.
After bidding Preston farewell, we drove up the road to our final site, Devil’s Gulch, where we met another restoration expert, Eric Ettlinger. That very day was Eric’s 20th anniversary as an aquatic biologist with Marin Municipal Water District (MMWD). Eric explained MMWD’s responsibility for providing safe drinking water for county residents and how they mitigate the impacts of the water storage projects by monitoring salmonids and enhancing available habitat. After a lunch-time Q&A session with Eric, we walked down to the final restoration site.
The Importance of Woody Debris
This site was a Trout Unlimited project, so Erik Young took the lead on describing the goals of this restoration. This project was installed several years ago and was fairly inexpensive compared to the previous two sites that we visited. At this site, large redwood logs, anchored to boulders with cables, were wedged into the stream. These logs and other masses of wood (known as “large woody debris”) have a variety of benefits for streams and salmonids. Large woody debris in a stream slows the flow of water, which reduces erosion, promotes groundwater recharge, and creates pools. These deeper pools are great habitat for rearing salmonids that need cooler waters. Large woody debris also collects other floating debris and promotes algae growth which creates micro habitats for invertebrates which are a food source for salmonids. Large woody debris also provides salmonids with cover from predators and shelter from turbulent flows. After drilling home the benefits to installing, or just leaving in place, large woody debris, Sarah had the students complete an activity on designing a large woody debris installation. At the end, everyone had their own version of the design which illustrated the point that there are many ways to engineer a restoration, and that sometimes it’s just trial and error…and a little adaptive management!
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