One question we have asked ourselves about the two gravel augmentations we have done on a side channel of the Boise River (in 2000 and 2003), is how long the gravel we added has stayed in the side channel. To help answer that question, as well as determine if another gravel augmentation on the Owyhee River would be worthwhile, we designed a "Gravel Tracking Project", led by BVFF member (and retired geologist) Jeff Jones. Jeff investigated several methods for tracking gravel movement and met with people from local company Biomark, who specialize in tracking fish with small PIT tags. Working with engineer Nick Porter from Biomark, we designed a study to use PIT tags to track gravel movement. Jeff led some "rock parties" where BVFF volunteers drilled small holes in 200 pieces of gravel and epoxyed in the small PIT tags.

Yesterday, a small team of BVFF volunteers placed 144 pieces of tagged gravel into 4 study plots at different gravel depths. Over the next 5 years we plan to scan for those tags each fall to see how long they stay in place. If enough gravel stays in place, and ODFW's fall spawning surveys show brown trout are using the gravel for spawning, then the club will start working on a second gravel augmentation.

The club is working with the Army Corps of Engineers, the Idaho Department of Water Resources and Ada County on a plan to place the remaining tagged pieces of gravel into our side channel. If all goes well we hope to do that before flows increase in the spring.

Thanks to our volunteers who helped tag and place the rocks. And a special thanks to Nick and Biomark who have been very generous with their time and use of equipment to do this study. We couldn't have done it without them.

#CoolScienceStuff

Setting up a Study Plot

Troy and Ken setting the depth of the flow-meter.

Pete and Jeff placing a piece of gravel 4 inches below the surface.

Nick Porter from Biomark scanning to make sure we can detect the tagged gravel.

Pete and Mike drilling gravel for PIT tags

 

The Gravel Gang