California Department of Parks and Recreation (DPR) has completed a Final Initial Study / Mitigated Negative Declaration (Final IS/MND) for the Malakoff Diggins State Historic Park (MDSHP) Sediment Control Best Management Practices and Habitat Restoration Project.

MDSHP is located in Nevada County approximately 9 miles northeast of Nevada City. The central feature of MDSHP is the historic hydraulic mining area that composes Malakoff Diggins basin, which provides important cultural, biological, and recreational values and opportunities.

However, stormwater runoff from the basin carries sediment and other pollutants that adversely affect downstream water quality. To address Waste Discharge Requirements (WDRs) issued by the Central Valley Regional Water Quality Control Board, DPR has designed sediment control components to be installed and maintained in the basin to reduce sediment discharge while minimizing the effects of the sediment control measures on the important qualities of MDSHP.

The sediment control components include a rock grade control structure and brush barriers to capture coarse sediment in the eastern portion of the basin, a swale to divert stormwater runoff for longer retention within the basin, and a soldier pile wall to slow stormwater discharge from the basin and increase sediment retention within the basin.

DPR circulated a Draft IS/MND for public review and comment from November 18, 2022, to January 18, 2023. The Final IS/MND includes an appendix with the comments received and DPR’s responses to the issues raised in comment. In consideration of comments and in furtherance of DPR’s stewardship of cultural, biological, and recreational resources, DPR refined the project to eliminate previously proposed testing and potential use of flocculant and soil stabilizers and to incorporate specific habitat restoration components, including:

  1. Active willow restoration to accelerate habitat benefits for Little Willow Flycatcher and other wildlife species;
  2. Non-native bullfrog management to benefit Foothill Yellow-Legged Frog, Western Pond Turtle, Little Willow Flycatcher, and other native species;
  3. Western Pond Turtle habitat enhancement to increase suitable basking and nursery elements; and
  4. Invasive plant removal and revegetation with native species to enhance native plant communities and prevent further spread of non-native plants.

A complete description of the sediment control measures and habitat restoration components is provided in the Final IS/MND. The analysis in the Final IS/MND concludes that, with implementation of project requirements and mitigation, the project would not result in any significant adverse environmental impacts and the project would improve habitat within the Malakoff Diggins basin and improve water quality and aquatic habitat in downstream receiving waters including Diggins Creek, Humbug Creek, and the South Yuba River.

DPR appreciates the agency and public comments that were provided on the Draft IS/MND. Input from all commenters fostered consideration of important refinements that have improved the project by providing additional environmental protection and environmental benefits including habitat restoration.

The Final IS/MND is available at DPR’s Internet webpage at:

Questions regarding the project should be directed to Dan Canfield, District Superintendent, Sierra District, P.O. Box 266, Tahoma, CA 96142-0266 or by email at