Hydraulic Mine Restoration

With over 1,500 abandoned hydraulic mines in the Sierra Nevada contributing sediment and mercury into streams and rivers, there is a lot of restoration work to do to restore forest health, protect our water infrastructure, restore wildlife habitat, and improve water quality. These sites in major rain events carry sediment and mercury from the site into nearby waterways. The Presence of hydraulic mine sites is a significant predictive variable for elevated fish mercury concentration in downstream water bodies (Alpers et al., 2016).

The Sierra Fund through past lab work, field testing, conducting a cost-benefit analysis, and implementing a pilot project has identified an innovative approach to restoring abandoned hydraulic mine-scarred lands and restoring forest health. We are working to turn our pilot project into a demonstration site, expand to more sites to further hone this restoration approach, and scale up restoration across the Sierra.

Innovative Pilot Project Restoring Hydraulic Mine

The Sierra Fund is demonstrating how to restore an abandoned hydraulic mine site and do an integrated forest health project. Grizzly Creek hydraulic mine site is in the Tahoe National Forest, in the Middle Yuba watershed. Testing has shown this site, like other abandoned hydraulic mine sites, contributes significant amounts of sediment to nearby streams and rivers impacting water quality and wildlife during surface runoff events.  Today, mercury that was used to aid in the gold recovery process some 170 years ago can still be found running off the site during rain events. Phase one restoration at Grizzly Creek included thinning fuels on the site to reduce wildfire risk and using ‘small diameter wood” material from fuel load reduction to create Process-Based Restoration (PBR) structures that capture sediment and reduce erosion. The structures include, Post-Assisted Log Structures (PALS), Zuni Bowls, and One-Rock Dams (ORDs) and are constructed with Symbiotic Restoration.  TSF also applied biochar on the mine site to improve soil health, soil structure, and act as a passive filter to improve surface runoff water quality. Our staff scientists, first in the lab and then on the site, constructed test plots and completed monitoring and found that biochar applications resulted in significant improvement in reducing suspended sediment and particulate-bound mercury in the runoff. Site treatments improve water quality, improve downstream habitats, and have the added benefit of sequestering carbon in the biochar to benefit the climate. This is the first project of its kind combining hydraulic mine restoration, fuel load reduction, and other watershed restoration improvements. Phase two of this pilot project will apply biochar across the entire denuded area, improve and expand the erosion control structures, and complete the fuel reduction for the surrounding acres.

Tours of Grizzly Creek Diggins Restoration Available

There is nothing like touring to better understand the scope of problems and solutions. The Sierra Fund has been taking conservation leaders, funders, agency staff, restoration business leaders, tribes, and others on tours of the pilot project site at Grizzly Creek. Tours feature not only the restoration site – but other upstream hydraulic mine sites, debris control dams filled with sediment from hydraulic mining practices, and the local creeks and forests in their current state. Through informal conversations and time with our staff scientists, tour participants learn firsthand about the extent of hydraulic mine impacts and more importantly innovative solutions. If you are interested in attending a tour, contact Jenny.Michael[at]sierrafund.org.

Analysis Shows Upper Watershed Investment in Hydraulic Mine Restoration Saves Money

The Sierra Fund developed a report, Benefit-Cost Analysis of Hydraulic Mine Restoration in the Middle Yuba and Oregon Creek Watersheds, with the World Resources Institute, Blue Forest Conservation, and the Yuba Water Agency. In this report, we quantified the amount of sediment coming from hydraulic mines in two watersheds and then estimated the costs of doing hydraulic mine restoration in the upper watersheds and compared that to the sediment removal costs at downstream water supply infrastructure. Two facts summarize the key findings of this cost-benefit analysis report

  • 80-90% of the sediment in the Log Cabin Dam and Our House Dam is from upstream abandoned hydraulic mine sites.
  • For every $1 spent restoring the sites upstream, $2.9 dollars are saved in downstream maintenance.

The analysis for water agency savings does not account for other priority co-benefits from the mine restoration – such as reducing the mercury load that runs off these sites and that can contribute to downstream accumulation in fish, sequestering carbon on site that helps address climate change, improving the sites vegetation and wildlife habitat, and reducing the risk of catastrophic wildfire.

Expanding Hydraulic Mine Restoration in Tahoe National Forest

The Sierra Fund is curating a prioritized list of hydraulic mine sites that can be restored in Tahoe National Forest. The Sierra Fund’s long-term goal is to restore over 150 sites in the central Sierra and we are recruiting new partners every day. Whenever possible we integrate fuel load reduction treatments, restoration of the watershed, removal of invasive species, and other actions to a more holistic approach to forest health.

Some founding partners to do more abandoned hydraulic mine restoration around the region are Yuba Water Agency, US Endowment, Tahoe National Forest, Blue Forest Conservation, Symbiotic Restoration, and Mooretown Rancheria. Mooretown Rancheria (Concow-Maidu) is expanding its forestry workforce to offer the inclusion of hydraulic mine restoration as part of its forest health work. The Sierra Fund is advocating that federal landowners give tribes the first right of refusal for doing forest health and hydraulic mine restoration through Service First agreements.

We secured California state funding to do community outreach and advance permitting and planning to restore more sites. We strive in all hydraulic mine restoration work to restore the resiliency of the forest.

Scaling up Hydraulic Mine Restoration: Leveraging Resources, Leading Trainings, and Supporting Networks

To restore the hundreds of abandoned hydraulic mines throughout the Central Sierra, the region needs significant investment, a broad network of restoration practitioners, and broad support. The Sierra Fund advocates for Forest Health work to include hydraulic mine restoration. We are also advocating that local, state, and federal agencies and private philanthropy increase investment in this work. To ensure there is a multitude of skilled practitioners to do the work (private/public), we co-lead the Process Based Restoration Network and are working with a subcommittee to co-develop permitting, training, and protocols for Process Based Restoration actions on hydraulic mine sites.