BC Hydro has been periodically releasing small volumes of water over the Revelstoke Dam spillway since April 25, 2018 during low energy demand periods.
This is a common operation during the spring when water is plentiful and there is reduced demand for electricity.
They are using the spill releases to maintain the minimum fish flow required downstream from Revelstoke Dam during low demand periods when it is less economic to generate power from our generating units.
Spill releases from Revelstoke Dam are most likely to occur overnight but can also occur occasionally during the day.
The decision for these small spills is typically made an hour or so before the spill starts so BC Hydro is unable to provide advance notification.
These small spills are very different than the large spill releases in high water years when inflows into Revelstoke Reservoir are greater than what can be discharged through the generating units.
When this happens, they need to release extra water over the spillway to maintain the Revelstoke Reservoir water level below its water licence limits.
The last large spill was in 2012, when discharges from the Revelstoke Dam spillway approached 30,000 cubic feet per second.
In events like these, they notify the public because they usually know a week or so in advance and the spill releases occur over a longer time frame i.e. multiple days instead of a few hours.
These large spills do not happen very often.
Prior to 2012 the last time they had large spill releases was 1997. At this time, they do not anticipate a large spill from Revelstoke Dam this year.