TSF Releases New Technical Report on Malakoff Diggins and the Humbug Creek Watershed

Watershed Assessment and Management Recommendations Released for Malakoff Diggins State Historic Park

Humbug-rept-Cover-4webToday, The Sierra Fund is releasing a new report, the result of more than five years of collaborative science-based data collection, research, and analysis at Malakoff Diggins State Historic Park (MDSHP), part of the California State Parks system. Key partners in this project, in addition to State Parks, include CSU Chico Geological & Environmental Sciences Department, Sonoma State University Archeology Department, California Department of Conservation/Abandoned Mine Lands Program (DOC/AMLP), Sierra Nevada Conservancy, and the South Yuba River Citizens League.

Click here to view the full 216-page report, or click here to view the 8-page executive summary.

MDSHP is the site of the mine that was the subject of the famous “Sawyer Decision” that ended hydraulic mining in the state. It preserves and interprets the 1850-s – 1880’s hydraulic mining era, when gold seekers combed the Sierra foothills and washed away whole mountains looking for precious metals creating the diggings.

The newly released Report outlines an assessment of the various physical and chemical characteristics of this legacy hydraulic mining park, including the pit or “diggins”; tunnels and shafts from the old mining operation; and the discharge from these features into downstream watersheds. The assessment portion of this Report used a variety of methods to learn about the nature of the pit itself as well as the Humbug Creek (into which the “diggins” discharge) including:

  • Historical research into mine operations prior to state acquisition (roughly 1850s – 1960s)
  • Sampling of soil and water and testing by EPA-certified laboratories
  • Continuous stage and turbidity recording to calculate annual loads
  • Event-based storm sampling for total suspended sediment and mercury
  • Physical surveys of the pit and surrounding area using GIS

This Report presents management recommendations about how to mitigate the physical and chemical hazards assessed by this project. This includes a provisional review of potential impacts under CEQA to identify studies needed to potentially permit the scenario of management recommendations outlined in the document. While some steps to abate identified physical hazards will be taken immediately, a final management plan, implementation strategy and environmental review will be only be completed after a thorough cultural resources inventory and evaluation of this historic landscape is completed and a cultural landscape plan developed and approved that allows historic resources to be protected as part of the final project.

Physical hazards detected included open air shafts and exposed tunnels that are easily accessible. Recommended measures include taking action to fence off physical hazards. The Department of Conservation Abandoned Mine Lands Program (DOC/AMLP) has already provided expertise and resources to take action on some of the physical hazards. Chemical hazards documented incorporate the development of new understandings of the fate and transport of legacy mercury used as part of 19th and early 20th century gold mining processes.

“We are looking carefully for additional point sources of mercury in the hydraulic mining pit. We have documented that the majority of the mercury currently discharging from the pit is bound to sediment, fine silts and clays, and moves primarily during large storm events” notes the report’s principal author, Dr. Carrie Monohan, Science Director of The Sierra Fund. “It is likely that reducing the discharge of sediment from the pit would help reduce mercury discharge from this source.” One recommendation suggests that further evaluation of creating a “settling pond” using the pit and passive filtration and/or possibly precipitating agents may be a way to remove mercury from the discharge and send clean water down the tunnel and into Humbug Creek.

The Sierra Fund, the leading environmental organization in the state working to assess and address the legacy of the 19th century gold rush, is releasing this report as part of the public education program leading up to their third major conference next week. Reclaiming the Sierra, a conference to be held April 20 – 21, 2015 at Sacrament State University, features a  tour of the Malakoff Diggins State Historic Park led by experts that are working with The Sierra Fund who is leading the project at the Park. Click here to learn more about the conference and tour.

Funding to evaluate management methods in more detail to reduce mercury and sediment discharge from the pit are underway, funded in part by a grant awarded to The Sierra Fund by the California Department of Water Resources, as well as from funding provided by the California Department of Conservation’s Abandoned Mine Lands Program.

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