Leavenworth Creek Watershed Restoration Project
Lauren Duncan1*
1Trout Unlimited, Abandoned Mine Restoration Project Manager, Rollinsville, Colorado, USA; lduncan@tu.org, 720-276-3889
Trout Unlimited (TU) and the US Forest Service (USFS) have been involved in on-the-ground watershed-scale restoration in the Leavenworth Creek Watershed since 2014. Leavenworth Creek is a headwater stream flowing into South Clear Creek and is a drinking water source for Georgetown, CO. The watershed is home to numerous mines including the Santiago mine and the Waldorf mine and an extensive swath of dispersed tailings below the Waldorf mine.
Leavenworth Creek was heavily sampled for water quality between 2011-2013 at 27 sites throughout the upper watershed. Sampling at the Waldorf dispersed tailings showed concentrations of Cd, Pb, Zn, and Cu above benchmark screening levels. Zinc loading rates increased from 8.2 tons/yr upstream of dispersed tailings to 12.5 tons/yr below dispersed area. These sampling results prompted the initial construction in the watershed. TU and the USFS installed a rip-rap ditch in 2015 to prevent surface erosion and sheet flow from the dispersed tailings entering Leavenworth Creek.
Once this ditch was constructed, TU and the USFS began restoration at the Santiago mine, a popular recreation site within the watershed. Soil sampling at the mine had revealed elevated arsenic, lead, and iron above recreational and interpretative visitor regulatory levels. Throughout 2016, project partners removed approximately 5,000 cubic yards (CY) of tailings material from the Santiago mine, constructed erosion controls, completed restoration at the historic mill building on site, and worked with the Colorado Division of Reclamation, Mining and Safety to secure the mine’s adit entrance.
Throughout 2017, TU and the USFS completed restoration of the Waldorf dispersed tailings area. The intent of this work was to reduce sediment loading from the tailings into Leavenworth Creek, eliminate potential exposure pathways for visitors and animals, and establish native vegetation throughout the floodplain. Restoration of the tailings included amending the tailings material with limestone, compost, Biochar, and Richlawn (a natural fertilizer). Project partners also built a small repository for approximately 1,000 CY of tailings. The entirety of the project area was seeded with native seed and covered with weed-free agricultural straw and Woodstraw. During this 2017 project, construction crews also revegetated the slopes at the Santiago mine.
Project partners completed necessary vegetation maintenance on the dispersed tailings areas and constructed buck and rail fencing at the Santiago mine in 2018. Soil testing throughout the dispersed tailings in 2018 indicated that the pH of soils in all restored areas are circumneutral and will sustainably support healthy native plant communities. Today, a reproducing boreal toad community has established below the restored floodplain and the riparian zone of Leavenworth Creek is flourishing.
Our hope in sharing this multi-phased project is to share our methodologies as a tool for others and to encourage other practitioners to take a watershed-wide, partner-based approach to restoration projects.