Headed for the Mountains
Join Date: Jun 2007
Location: Calgary, AB, Canada.
With a good design, a run-of-river scheme should have minimal impact to salmon stocks; however, there are some critical considerations:
1) water availability (dewatering of the diversion reach - likely not totally dry, but reduced)
2) impact to spay zone ecology (saprolites (sp.?) and other humid environment flora/fauna rely on waterfall spray zones (important for ecological diversity)
3) sediment recruitment (ability to transport sediment in a natural degradation/aggradation regime) - this effects the recycling of habitat units where salmon and other fish species may spawn
4) nutrient loading
5) water temperature (if there is >7 day storage involves - not typical for run-of-river it can raise the water temp resulting in a less favourable environment for fish and benthics)
6) ramping - when the intake gates are opened/closed there is a leading or trailing wave of water that can leave portions of the stream high and dry if the ramping rates are well defined
Each of these can be mitigated through good design and operational strategies. If you think that the process for the review is inadequate, you should lobby for an independent cumulative effects assessment. remember that BC Hydro is under no obligation to sign an energy purchase agreement (EPA) with am IPP. It can choose to accept all, some, or none of the projects based on their economic and environmental merits and proximity to load centers and/or existing transmission infrastructure.