The Oregon Watershed Enhancement Board (OWEB) and the Washington Salmon Recovery Funding Board (SRFB) are currently working cooperatively to monitor livestock exclusion projects in both states as part of a "project-scale" effectiveness monitoring program for watershed and salmon habitat restoration projects. Livestock exclusion has been identified as an important action for restoring fragile riparian areas. Livestock exclusion includes building and maintaining fences along riparian areas. Project data and results are shared between the states. This coordinated approach represents a successful effort to collect comparable and compatible data across jurisdictional boundaries.
This project employs a Before-After-Control-Impact (BACI) design. A BACI design means that data is collected both "Before" and "After" an impact, in this case the impact is fence building. The “Control” is established in areas not expected to change during the project. The "Impact” is where the impact will occur. This specialized design helps to isolate changes caused by an Impact by comparing the present condition of the impacted reach against both the present Control conditions and the Before conditions. This project is collecting data addressing: livestock presence in the exclusion, bank erosion, and riparian vegetation structure at each project site. Monitoring takes place one, three, five and ten years after fence installation.
OWEB and SRFB contracted with Tetra Tech EC, Inc. to monitor the effectiveness of twelve livestock exclusion projects. The final report for baseline sampling (Year 0) and the Year 1, Year 3, and Year 5 are posted below.
When data from Oregon and Washington are combined the latest preliminary results (2012 Annual Report) indicate that:
- Percent of Functioning Projects
Year 1: 83% of monitored project sites were effective in keeping livestock from riparian areas.
Year 3: 75% of monitored project sites were effective in keeping livestock from riparian areas.
Year 5: 64% of monitored project sites were effective in keeping livestock from riparian areas.
- Bank Erosion
Year 1, 3, and 5: A statistically significant reduction in Linear Proportion of Actively Eroding Banks is evident.
- Riparian Vegetation
Statistically significant results were not found for changes in Canopy Density.
* However ‘…a slight average increase in canopy density following project implementation was apparent when comparing average pre-project and post-project conditions (Figure 5).’
Statistically significant results were not found for Riparian Vegetation Structure.
* However ‘…it has shown an improving trend toward change, as shown in the slope box plot. (Figure 3).’
These results are promising and begin to shape the understanding of the importance of livestock exclusion as a restoration action that improves stream quality.
A few lessons learned from the projects are:
- Riparian planting may also be needed at the time of fencing is installed to advance riparian diversity.
- Invasive species control in the exclusion may also be necessary to allow native species to mature.
- In some cases, uncontrollable natural events, such as trees falling across the fence structure, resulted in a project being non-functional. However, in other cases, clear evidence of livestock access to the stream due to improperly installed or maintained structures was found. (2012 Annual Report)
- It is imperative that fences are installed with the intent to exclude livestock from the stream for the life of the project or longer and that they are maintained in properly working condition.
Next questions about livestock exclusion effectiveness monitoring that could be addressed include:
- How do livestock exclusions affect fish populations and growth at a broader scope?
- How do livestock exclusions affect the influx of sediments, nutrients and pesticides?