Description:
Excavated pools, large woody debris and constructed spawning gravels were used to increase the available trout habitat in Warm Springs Creek near Mackay, Idaho. The dominant habitat type in the stream prior to construction was a low gradient riffle approximately 12' deep. In 5 days, we constructed 35 pools with depths ranging from 3-4' in depth, placed 40 pieces of large woody debris (cottonwood logs) as cover in the pools and log drop structures to promote long-term scouring, and constructed 12 artificial spawning beds using imported gravels. Immediately after construction, large fish from an off-channel, connected pond moved into the created habitat and began holding in the excavated pools and feeding in constructed feed lanes. Over the course of several years, however, flows undercut some of the log drop structures because the substrate was dominated by a surface veneer of gravels covering 2-4' of fine sand. In 2007, Intermountain Aquatics returned and installed a geo-grid fabric upstream of the undercut logs to prevent undercutting. Gravels were then placed over the geo-grid and compacted. We will continue to monitor these structures assess of the effectiveness of this method in this unusual sandy stream system.