Measuring the Big Wood River’s Health

 

The Big Wood River of Idaho is getting a check-up, and recent findings indicate that there are opportunities to improve the river’s health.

 

Trout Unlimited and the Wood River Land Trust recently began a partnership called the Big Wood Home Rivers Initiative. The goal of the initiative is to restore, protect, and sustain the full, wild-trout potential of the Big Wood while fostering the community that has grown around this iconic western river. 

 

To that end, TU and the WRLT, along with the U.S. Forest Service and Bureau of Land Management, have undertaken a comprehensive, watershed-scale physical, hydrological and biological assessment of the Big Wood. The study area encompasses 30 miles of the river, from the North Fork to its confluence with Magic Reservoir. In order to address concerns – including lower flow, habitat loss and increased water temperatures – it is critical to understand healthy river function and ecology and to acquire the data needed to identify problems, as well as to measure improvements created through restoration, reconnection, and habitat improvement projects.

 

One concern for the health of the Big Wood River is its ability to transport sediment effectively. Today, many reaches of the Big Wood no longer have that capacity, reducing the river’s ability to access its floodplain and create riparian habitat. Recent forest fires, such as the Beaver Creek fire of 2013, have resulted in catastrophic runoff and debris flows, compromising river substrate, impacting aquatic insect populations, and reducing suitable spawning gravel for resident trout. 

 

While we have no control over the forces of nature, what TU can do is improve river health and functionality, making it more resilient to catastrophic events and allowing the river to effectively transport sediment throughout its course. If functioning properly, a river such as the Big Wood should be able to transport and deposit sediment in the river channel where appropriate, allow transported sediment to be deposited along the floodplain (essential for a healthy riparian zone), and move various-sized substrate. All of this translates into improved aquatic and riparian habitat for the river’s wild rainbow trout. 

 

The final assessment report from Biota Research & Consulting was delivered to TU in November 2015. Project partners are planning a public meeting for February 2016 to discuss the study’s findings and development of river restoration projects from that study. 

 

The assessment has already led to the development of a key habitat and river enhancement project that will be implemented in 2016. The project area is located south of Ketchum near the Sheep Bridge along Highway 75 (near the Hospital), and will focus on restoring stream-bank stability, habitat complexity and river functionality to a half-mile section of the river. The project will also give adjacent property owners an opportunity to restore habitat for resident trout while providing an ecologically sensitive approach to maintaining their property. Project implementation will begin in 2016, dependent upon funding and permitting.