August 1, 2014.
Human activity in central valley streams has had a significantly negative impact on salmon habitat (Williams 2006). The presence of dams impedes sediment transport which is critical to salmon spawning (Williams 2006; Kondolf 1997). As part of an effort to enhance salmon spawning, the California Department of Water Resources added 7000 ft3 of gravel to Cottonwood Hatchery, Upper Auditorium, and Auditorium riffles on the Lower Feather River below the Thermalito Dam Complex in July of 2014. Stream conditions at Cottonwood Hatchery riffle were assessed by conducting analysis of sediment grain size, water depth and velocity, gravel permeability, and dissolved oxygen content. Grain size analysis of the surface layer was conducted via the Wolman pebble-count method. Subsurface bulk samples were collected, weighed, and then separated using rocker sieves to determine grain size distribution. Water depth and velocity measurements were collected according to USGS stream gaging procedures (1980). Gravel permeability measurements were taken using the Barnard-McBain standpipe method. Dissolved oxygen data was collected using mini-piezometers. These results were compared to data from Heffernan (2013) which were taken prior to the addition of gravel. The measurements taken in 2013 before the addition of gravel reflect hyporheic conditions that are poor for salmon spawning. Data collected after the addition of gravel in 2014 suggest that conditions in the Cottonwood Hatchery Riffle will be much more suitable for spawning salmon.
Aquaculture and Fisheries | Geology
California State University, Sacramento (Sac State)
This material is based upon work supported by the Howard Hughes Medical Institute (HHMI). Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of HHMI. This work was administered by the Cal Poly Center for Excellence in Science and Mathematics Education (CESAME) and the Fresno State Science and Mathematics Education Center (SMEC) on behalf of the California State University.