. The Big Blackfoot River restoration progress report for 2002 and 2003 . Fish populations; Fishes; Fishery management; Trout fisheries; Stream ecology; Blackfoot River (Mont. ). Percent. 126 Size class (Inches') Figure 44. Pebble count particle distribution at bankfiill riffle cross-sections in three reaches of the upper Blackfoot River. Mean wetted widths (pools and riffles) and pool length all increased in the downstream direction. Mean residual pool depth decreased from ' in the upper reach to ' (middle reach) to ' in the lower reach. We completed pebble counts
. The Big Blackfoot River restoration progress report for 2002 and 2003 . Fish populations; Fishes; Fishery management; Trout fisheries; Stream ecology; Blackfoot River (Mont. ). Percent. 126 Size class (Inches') Figure 44. Pebble count particle distribution at bankfiill riffle cross-sections in three reaches of the upper Blackfoot River. Mean wetted widths (pools and riffles) and pool length all increased in the downstream direction. Mean residual pool depth decreased from ' in the upper reach to ' (middle reach) to ' in the lower reach. We completed pebble counts for both the bankfiill (Figure 44) and wetted-width (riffle-crest) cross-sections. For the wetted-width surveys, we recorded a large decrease in suitable spawning-size (') gravels in the downstream direction. In the upper reach cross-section, we found well-sorted substrate ranging from a ; to ; diameter with 89% of the surface substrate falling into the ; diameter size range. In the middle reach cross-section, we found alluvial gravel with a smaller range of particle sizes (compared v^th the upper reach) ranging from very fine sand to small cobble, a bimodal distribution with 19% of the sample comprised of sand (modal class), 28% <; diameter and 70 % of the sample within the medium to coarse gravel (;) substrate range. For the lower reach cross-section, we found a poorly sorted, more heterogeneous mixture of substrate in riffles, with a much wider range of substrate sizes ranging from clay/silt to boulder (<; to 20"). A veneer of silt and clay covered the surface and interstitial spaces of the substrate and only 28% of the sample gravels fell within the suitable spawning- size range. For bankfull measurements, we found a bimodal distribution at all three samples, with very fine sand and smaller particles being a dominant size-class. Water temperatures show a wide range of variability within and between
Size: 2318px × 1078px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcollectionamericana, booklea, booksubjectfishes, bookyear2004
