Elkhorn Creek at Dall

Cameron Peak Post-Fire Restoration

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:

• Beaver Dam Analogs (BDA) - BDAs are channel-spanning, semi-permeable structures with a uniform crest elevation constructed using live willow cuttings/branchy material and sod to mimic natural beaver dams. Live willow/lodgepole branch cuttings, burnt logs/branches, and sediment plugs will be gathered on-site and matted together in layers to create a wide berm. Posts made of untreated timber (2-4” diameter) 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 backwater area behind the structures which benefits habitat and floodplain connectivity. Note that this site had beaver activity immediately prior to the 2020 Cameron Peak Fire, and many of the locations of BDAs are to repair holes to existing dams. Willows gathered to use in the construction of these features will not exceed 20% of the total number of stems on an individual plant and would be harvested off-site in an approved harvest location. Branches taken from live trees on and/or off site will be taken in a manner as to not kill the tree. Live material to construct BDAs may include small (< 4” DBH) lodgepole pine trees of which no more than 33% would be harvested.

• Post Assisted Log Structure (PALS) – PALS would be placed primarily at portions of the main channel where overbank flows can be achieved or additional roughness would contribute to slowing water in an area that may currently have high velocity. On-site burnt logs/branches (< 15” dbh or less, < 33% of available trees) and live willow cuttings would be pinned together with untreated timber posts (2-4” diameter) driven into the streambed to initiate and simulate natural wood accumulation. PALS provide opportunities for sediment storage behind the structures while promoting overbank flow, additional wood recruitment, aquatic habitat complexity, and riparian health. PALS would be constructed by hand crews with a pneumatic post driver and chainsaws. An ATV will be needed to move the post driver set up to most PALS locations.

• 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.

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 Elkhorn 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

• US Forest Service

• Ayres Associates (Design & Engineering)

• Anabranch Solutions (Project Construction)

• Colorado State University (Research & Monitoring)
  

Funders

• Colorado Department of Public Health and Environment (CDPHE)

• Colorado Water Conservation Board (CWCB)

Project Timeline

Summer 2026 - Phase 1: Initial installation of in-stream features and willow staking

2027-2031 - Phase 2: Install additional in-stream features and willow staking on an as-needed basis.