Water Stewardship Information Sources

Citation Anderson, D. 2009. Salmon River adult fish passage assessment study. Prepared for BC Hydro.
Organization BC Hydro
URL https://www.bchydro.com/bcrp/projects/docs/07.CBR.04.pdf
Abstract/Description or Keywords The Salmon River is amongst the largest watersheds on Vancouver Island with a drainage
area in excess of 1200km2
. The 5.6m BCHydro diversion dam may interrupt access for
upstream migrating adult salmonids to over 50km of mainstem and tributary habitat in
268km2
of watershed upstream. The upper Salmon River has valuable Coho spawning
and rearing habitat (Craig et al. 1998, Wong, R. and V. Komori. 1999) that will become
increasing important with the effects of global climate change. Utilization of the entire
accessible watershed is important to the biodiversity of Coho populations; access to
headwater habitats will be key to salmonid survivals through warming periods. These
higher elevation habitats will warm the least and retain the most snow, as well as provide
some protection against the increased intensity of winter storm discharges. This pilot
study was initiated to determine if the returning Coho adults found the Fishway structure,
if they successfully transited the diversion facility, under what flow conditions, and if
possible understand the period of delay for upstream migrants. The results from the
resistivity counter and the acoustic tagging program do provide some insight into the
relationship of the migrating Coho to the changes in the Salmon River discharge; the
configuration of the undersluice gate opening, mainstem flows and diversion flows are all
important considerations in how the Coho behave. Mainstem discharges to 30m3
/sec,
with the undersluice gate opening to nearly 1 meter, resulted in net upstream Coho
migration, however with the undersluice gate decreased to 0.15m Coho were attracted to
the fishway, but net upstream counts were negative during most flows. Only a few
appeared to successfully move upstream through the fishway when the discharge to the
lower river was 10-12 m3
/sec (adjusted by subtracting diversion canal flows from
mainstem above the diversion). The acoustic tag information mirrors the resistivity
counter finding. This appears to point to some obstruction, whether velocity or
behavioural, within the fishway itself even at fairly low downstream discharges. Surface
water level differences, from the canal to river downstream, and turbulence within the
fishway will require further investigation.
The 2008 study has established a foundation of information, communications,
procedures and logistics that will be built on with the continuation of this study. Through
understanding the limits or bottlenecks, if any, to upstream migration of both Coho and
steelhead adults at the Salmon River diversion dam we can better formulate practical
solutions to adult upstream fish passage.
Information Type report
Regional Watershed Vancouver Island North
Sub-watershed if known Salmon River
Aquifer #
Comments
Project status complete
Contact Name
Contact Email