Following the Flow

Colorado Headwaters Restoration Science Program

Measuring the hydrologic and sediment impacts of processed-based beaver wetland restoration in Rocky Mountain headwater streams


Project Background

Process-based riverscape restoration broadly describes restoring the rates and magnitudes of historically significant hydrologic, geomorphic, and biological processes within the riverscape’s historical footprint (river or stream corridor within a valley bottom). Enhancing surface and subsurface water and sediment detention in headwater streams and wetlands (riverscapes) through process-based restoration has been touted as a tool to enhance the ecosystem services, this natural infrastructure may provide for downstream human needs. Among groups implementing these projects, there has been particular emphasis on the re-establishment of beaver and their works (ponds, dams, canals, etc) within riverscapes (beaver wetland restoration) given their potential to contribute to surface and groundwater detention and sediment capture without continuous human intervention. This project, therefore, is studying streams where beaver wetland restoration projects meet the following criteria:

1) GOALS: beaver recolonization and increases to surface and groundwater detention

2) PROCESS-PATHWAY: beaver mimicry structures induce geomorphic changes that support long-term beaver recolonization, maintenance and expansion

3) TACTIC: beaver mimicry structures


Research Questions

This project is investigating if and how beaver wetland restoration (defined in more detail below) changes the patterns of flows coming into and leaving the study reach as well as any changes in the volume of sediment that accumulates.

1. How does beaver wetland restoration influence surface and subsurface water detention, fluxes, and ultimately stream flow magnitude, duration and frequency at the reach scale (1 to 5 km)?

2. How does beaver wetland restoration influence where and how sediment is detained within a riverscape?

Read more about our research plan and methods  here. 


Jessica Doran of EcoMetrics Colorado and EcoWorks installing a beaver dam analogue structure in the headwaters of the South Platte River.

Beaver Wetland Restoration

In practice, process-based restoration (PBR) spans a wide range of restoration strategies and treatments. In general it aims to restore “normative rates and magnitudes of physical, chemical, and biological processes that sustain river and floodplain ecosystems” (Beechie et al 2010). PBR approaches range from “High-Tech”, which may include earth moving equipment and some level of engineering design and modeling, to “Low-Tech”, which can be accomplished with field design and use of natural materials to build temporary structures in support of process restoration.

In this study, we decided to focus on process-based restoration of stream-wetland systems in headwater watersheds that employ low-tech structural treatments that mimic, promote, and sustain natural levels of beaver activity—a strategy that is rapidly growing in use and popularity across the West. Restoration projects with the explicit goal of re-establishing beaver have the potential to detain relatively larger quantities of water and sediment compared to treatments or sites that do not have this goal. However, these projects are subject to the uncertainty and variability associated with beaver mediated natural systems (Nash et al., 2021). Low-tech PBR typically involves the use of beaver mimicry structures (BMS) and post-assisted log structures (PALS) to detain water and sediment, raise the water table, and improve stream conditions for beaver colonization. Ideally, beavers take over maintenance and creation of these structures over the long term.

Each monitoring site slated for restoration has its own unique geography, restoration goals, and project partners. However, all sites either have had beaver established within them in the recent past and/or have some level of beaver presence in or proximal to them.

 Beechie, TJ, Sear, DA, Olden, JD, Pess, GR, Buffington, JM, Moir, H, Roni, P, Pollock, MM. (2010) Process-based Principles for Restoring River Ecosystems, BioScience, 60(3): 209–222,  https://doi.org/10.1525/bio.2010.60.3.7   

 Nash CS, Grant GE, Charnley S, Dunham JB, Gosnell H, Hausner MB, Pilliod DS, Taylor JD. (2021) Great expectations: Deconstructing the process pathways underlying beaver-related restoration. BioScience. 71(3): 249–67.  https://doi.org/10.1093/biosci/biaa165  


Timeline


Monitoring Locations

Project Details

Explore our project sites and monitoring locations in detail, below. Zoom and scroll through these hi-resolution aerial images to see how and where we are monitoring streamflow and groundwater. You may also expand the aerial images using the full screen button on the top right. Once these sites have been restored, you will be able to visually explore the changes that result each year.

Fish Creek 

The Estes Valley Watershed Coalition has been supporting beaver wetland habitat and working to restore beaver wetlands on Fish Creek since the 2013 floods and subsequent emergency repair work severely impacted this creek. The current creek alignment resulted from emergency stabilization measures and lead to approximately six feet of incision through the site, lowering the water table, and disconnecting and drying out the surrounding beaver meadow. One mainstem beaver pond was established in 2023 and several tributary beaver ponds have existed on the site for decades. Restoration work planned for 2026 will plug this channel and re-direct flow to the north side of the valley in the historical channel footprint. It is hoped that this work will facilitate further beaver re-colonization of the site by downstream colonies.