Elkhorn Creek at Dall

Cameron Peak Post-Fire Restoration

 

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Project Overview

The purpose of this project is to improve water quality and riverscape resiliency following impacts from the 2020 Cameron Peak Fire on Elkhorn Creek, a tributary to the Cache la Poudre River. This project will be funded by National Forest Foundation that focus on water quality improvements, sediment capture, and improving riparian ecosystems across the burn scar.

A significant portion of the watershed contributing to this site was burned during the Cameron Peak Fire. CPRW and Ayres completed a prioritization matrix in which this watershed ranked third out of over two dozen sites across the Cameron Peak Fire burn scar. This section of Elkhorn Creek was inhabited by beavers immediately prior to the fire. Since then, the channel has experienced severe incision and floodplain discontinuities that impact riparian health and water quality in Elkhorn Creek and the Cache la Poudre River. Prior to the fire, there were extensive stands of willow and other brushy vegetation in the project area. However, that vegetation has not yet been able to recover due to sever browsing.  This project would contribute to the landscape level approach for low-tech process-based mitigation within the Elkhorn Creek watershed.

A combination of burnt woody material in addition to live willow and lodgepole branch cuttings will be used in this project to slow channel flows, deposit sediment, and encourage more regular overbank flooding that would support healthy riparian ecosystems. Beavers were active at this location through 2020 and, while not dependent on the return of beaver, this project would contribute to improved beaver habitat. Our goal is to tip the scales in the beavers favor by providing them with building materials, ideally so they can maintain structures over time in addition to the many ecologic benefits beaver provide. Out of the LTPBR projects in the area, this particular project area had the most extensive, robust, and recent beaver population. Encouraging beaver back into this area may create a “beaver launch pad” for the several other nearby projects.

Post-Fire Treatments

CPRW proposes to use low-tech process-based restoration (LTPBR) techniques and structures to improve water quality and riverscape resiliency following the 2020 Cameron Peak Fire along Elkhorn Creek. The proposed location was chosen because severe and significant portions of burnt area is contributing to the site which have caused degradation to Elkhorn Creek, a tributary to the Cache la Poudre River. Low-tech means that features will be installed with hand crews only (no large machinery) within the project area. Given the presence of beaver in 2020 in the project area, the design is flexible to avoid disturbing or displacing beaver and assumes at least a 150 ft buffer around any potential future beaver activity. A contractor will construct all process-based mitigation features using hand crew techniques. CPRW proposes the following features:

  • Post Assisted Log Structure (PALS) – On-site logs are stabilized using untreated posts driven into the streambed to initiate and simulate natural wood accumulation. PALS provide opportunities for sediment storage behind the structures while promoting floodplain connectivity, additional wood recruitment, and riparian health. PALS function best in streams with high sediment loading, like the fire-affected Sheep Creek, and in series to allow for wood movement within the system. These features are intended to target annual storm events and are not expected to remain intact during the 100-year flood event.

    Burnt logs/trees will be gathered from adjacent areas and used to construct the PALS. Typically, each PALS will have approximately six logs of which two will be at least the channel width. When possible, logs with rootwads will be used to stabilize PALS and create more complexity. Other stabilization techniques include ballasting into existing vegetation or topography and tying with thick manilla rope. The exact location and size of these features will be field fit by the design team at the time of construction.

  • Install Willow Stakes – Establishing woody riparian vegetation such as willows increase the capacity for sediment storage and nutrient uptake and enhances habitat complexity in riparian and aquatic ecosystems. Native willows would be harvested off-site at an approved harvest location and installed at locations with shallow water tables and near constructed features that would support establishment. Willows gathered will not exceed 20% of the total number of stems on an individual plant.

  • Temporary Exclosure Fencing – This component of the project is to be determined based on input from USFS. Because many of the riparian willows were burned to ground level followed by overgrazing of cattle and ungulates, temporary exclosures may be an appropriate solution to allow for riparian recovery and support healthy beaver habitat. An ecologist will verify that overgrazing is restricting tall willow growth in the riparian area and used to determine the primary grazers at the site (cattle, deer, elk, moose, etc). Experimentation may include use of game cameras and evaluation of scat and tracks to identify grazers. If an exclosure is determined to be an appropriate mitigation technique given the driving factors for lack of regrowth, then exclosure fencing will be installed in strategic locations that target primary grazers. Temporary fencing would likely be constructed from fiberglass rod or wood posts (< 2” diameter) and solar powered electrical fencing to deter native ungulates and cattle. All temporary fencing would either be moved to a new location (if appropriate) or removed completely once willows have reached a mature height (3 or 4 years). CPRW would be responsible for experimentation, implementation, and removal of fencing. The exact location of fencing is to be determined in 2025.

  • Beaver Dam Analogs (BDA) - BDAs are channel-spanning, semi-permeable structures with a uniform crest elevation constructed using woody debris and fill material to form a pond and mimic natural beaver dams (Wheaton et al., 2019). Woody material and sediment plugs will be gathered on-site and matted together in layers to create a wide berm in secondary channels. Posts will be driven through the structure after reaching the final crest height in order to provide additional stability. BDAs mimic the form and function of natural beaver dams by creating a backwater area behind the structure, which benefits habitat and floodplain connectivity. These features will be field fit by the design team. Note that pervasive beaver dams existed throughout this reach prior to the Cameron Peak Fire and minimal beaver activity was observed in 2023.

 

Project Goals

  • Improve water quality and ecological functioning by providing opportunities for sediment storage, nutrient uptake, and enhanced aquatic and riparian habitats.

  • Improve stream processes in Sheep Creek that align with downstream Wild and Scenic recreation, aesthetic, fisheries, and aquatic habitat values in the Cache la Poudre River.

  • Use process-based restoration techniques to meet the project objectives.


Project Collaborators

  • Private landowner

  • US Forest Service

  • Ayres Associates (Design & Engineering)

  • Anabranch Solutions (Construction)

  • Colorado State University (Research & Monitoring)

Funders

  • Colorado Department of Public Health and Environment (CDPHE)

  • Colorado Water Conservation Board (CWCB)


Project Timeline

2026: Project construction

2027: Willow harvesting & planting

2027-2031: Adaptive management as needed - Depending on if beaver return and how the stream responds to Phase 1 features, additional BDAs and PALS may be needed to meet project objectives within the defined project area.