Over the past few years, state and federal resource agencies collected physical and biological data to investigate the effect of minimum flows and ramping rates on aquatic resources in the bypassed reach of the Cheoah River. Most physical and biological monitoring took place before, during and after high flow events in May and July 2007 and May 2008. Physical data collected included flow and temperature from the USGS gage; water depth (level logger) data at selected instream flow study transects used during relicensing; and resurveying the bottom profile of selected transects. Biological data included visual observations and photographs of fish nests; measurements of depth, velocity and size of fish nests; level logger data at fish nests; running the instream flow habitat model (PHABSIM) to assess the effects of ramping, and collection of larval fish in phytoplankton (drift) nets.
The results of these investigations are:
This report definitively finds that the high flow events that paddlers use on the Cheoah River have no significant biological or stream channel impacts that need to be addressed. Of course, the study failed to address the many benefits the flow regime is having (flushing fine sediment, controlling vegetation encroachment, selecting for native species, etc). Still, this report is a hallmark of the high value and benign nature of high flows in the Cheoah River.
Based on this report, it is now possible that flows could be tweaked to maximize environmental benefits in a manner that enhances recreational enjoyment. Of particular interest is a finding (in Table 13) that the high overnight flows currently required between releases may be better allocated to other times or days. This water could potentially be used to increase some peak flows or add additional release days. American Whitewater is very pleased that the releases on the Cheoah are a good thing for the river, as predicted, and will continue to work to restore the Cheoah River.
Read the report here.