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NOAA: Linking Fisheries, beaver, geomorphic and physical habitat monitoring data to better understand the effectiveness of restoration efforts in Bridge Creek


Project Type:  Sponsored Research
Project Sponsor:  NOAA Northwest Fisheries Science Center
Project Location: Bridge Creek, OR
Status:   Ongoing

Project Overview

Purpose of Project:

The purpose of this project is to assess the role of beaver in shaping steelhead trout (Oncorhynchus mykiss) habitat complexity and thermal refugia in Bridge Creek, tributary to the John Day River in central Oregon.

Abstract:

The incised and degraded habitat of Bridge Creek, tributary to the John Day River in central Oregon, is thought to be limiting the local population of ESA-listed steelhead trout (Oncorhynchus mykiss). Restoration efforts for this watershed involve partnering with beaver to encourage dam building activity to aggrade an incised channel, promote floodplain reconnection, and overall improvement of in-channel and riparian habitat quality and complexity. The restoration efforts are part of the Integrated Status and Effectiveness Monitoring Program (ISEMP), a program with goals to test monitoring protocols and restoration strategies for ESA-listed salmonid species in the Columbia River Basin. The restoration strategy being tested in Bridge Creek involves the installation of over 100 beaver dam support (BDS) structures that are designed to either mimic beaver dams or support existing beaver dams.

The overall objective of this study is to determine if the BDS structures have had an effect on stream channel habitat complexity and thermal refugia in selected sections of Bridge Creek. Analysis of stream temperature data in restoration treatment and control areas will show the effects of beaver dams on stream temperature. Analysis of aerial imagery and high resolution topographic data will exhibit how the number and types of geomorphic units have changed after the construction of beaver dams. Combined, the results of this research are aimed to increase our understanding of how beaver dams impact fish habitat and stream temperature.

Significance of Project:

This project will fill gaps in the literature, and will increase our understanding of how beaver dams impact stream temperature and stream channel geomorphology. The results of this project will
be aimed at on-the-ground restoration practitioners as well as researchers in this field.

Bridge Creek BDS Structures


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Figure 1. Bridge Creek study site map.

Methods

Data collection occurred from June 25 to August 21, 2012, and was completed at a total of 5 study reaches on mainstem Bridge Creek. There were two control reaches and three treatment reaches (“beaver influenced”). Average site length is 165 meters. The complete data collection for a site entailed topographic data collection with an rtkGPS, temperature data collection, blimp aerial imagery, geomorphic and hydraulic unit mapping, snorkel survey, and flow measurement.

A survey grade Leica System 1200 rtkGPS Base and Rover was used to collect high resolution topographic data of each site. This GPS unit was also used in combination with a temperature probe to map stream temperatures, and it was used to map geomorphic and hydraulic units. Temperature data was collected using Onset Hobo TidBit Pro v2 Water Temperature Sensors, Onset Hobo Pro v2 Water Temperature Sensors (U22 model), and an Omega HH41 High Accuracy Temperature Probe. The data from the rtkGPS/temperature probe combination will be used to map stream temperatures at a higher resolution than temperature sensors alone.

Temperature sensors were deployed at an average spacing of approximately two meters throughout each study reach. The sensors were attached to rebar driven into the stream channel, and were placed just above the bed surface. Temperature sensors collected data every five minutes, and were in-situ for at least a week at each study reach.

Aerial imagery of each study reach was collected using a blimp. Snorkel surveys of each site documented species, number, and locations of fish using the reach during the temperature data collection. 

Preliminary Results

  • When comparing the frequencies of stream temperatures observed in the Lower Owens treatment reach and Boundary control reach over the period of August 13-21, 2012, we found that the control reach had greater heterogeneity in stream temperature, but it also contained a higher number of temperature values that have been cited as lethal to steelhead trout (Wehrly et al., 2007) and a lower number of cooler temperatures that could be used as refugia.
  • The Lower Owens site temperature data exhibits areas of upwelling that was discovered in stream sections located downstream of beaver dams. Stream temperatures were observed to be up to ten degrees cooler in some areas of upwelling. It was also found that the heterogeneity in stream temperature is greater in the restoration treatment reach than the control reach, at the time period in which the surveys occurred, which was at the peak of the diel cycle

Preliminary Conclusions / Future Work

  • Based off of the stream temperature data from the Lower Owens and Boundary reaches, beaver dams appear to have an effect, thereby increasing the thermal heterogeneity at peak times of the diel cycle. In turn, it can be concluded that this restoration technique could have profound effects on the amount of available thermal refugia for endangered steelhead trout rearing throughout the warm summer months when stream temperatures often exceed lethal limits.
  • Future work will focus on completing the analysis of habitat complexity before and after restoration treatment, and tying these results together with the temperature analysis results.

Related Links & Research



Project Outputs

Presentations from this Project

  • Poster: Consolati, F.N., Wheaton, J.M., Neilson, B.T., N. Bouwes, and M.M. Pollock (2012), The role of beaver in shaping steelhead trout thermal refugia in a central Oregon stream, presented at 2012 Binghamton Geomorphology Symposium, Jackson Hole, Wyoming, 21-23 Sept.

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Florence Consolati,
Oct 7, 2012, 9:35 PM
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