The late Jack Morris of Kaslo had a rule of thumb about high water on Kootenay Lake. He would watch a patch of snow on the mountainside and he claimed that the spring flood would crest just as that snow melted.
I thought about Jack’s rule and it made good sense. At this time of year, the determining factors for the Lake’s level is inflow and the constriction at Grohman Narrows which limits the outflow. As the snow line moves up the mountain in the spring, at some point there isn’t enough snow left above it in the high mountains to melt and provide a greater flow into the Lake than out. At this point, the Lake level will start to drop.
Alas, I don’t know which spot Jack monitored, and even if I did, I wouldn’t be able to see it from my home. But, might I do even better by using the Redfish Snow Pillow—a guide to snow depth in the mountains that is available on line for all to see?
The first question is: As the snow on the pillow melts in the spring, at what (water equivalent) depth does the Lake level typically crest? After a few years of monitoring, it seems the value is about 700 mm (with some variation).
The second question is then: Can we predict when this year’s plot will descend to 700 mm? Yes, look at this year’s plot. It is the dark blue line. It looks as though it will track fairly close to the lighter blue line from a previous year. This crosses the 700 mm point on the final day of the month, or perhaps the first day of July.
Now, I am not so naïve as to believe that this approach captures all the variability possible: sudden warm spells, or extensive rain. Yet, it is probably not far off.
For now (June 8th) my expectation is that the Lake will not crest before the dying days of the month.
It is early June; the Lake is rising and hasn’t finished doing so.
your jack morris must have had some excellent eyesight. the spot he and many old timers are refering to, is know as the swallow (the wings have grown less distinctive over the years), high above procter on the procter ridge. it can be clearly seen from balfour and the central part of the lake, but i doubt that it’s visible from kaslo. here is a pix the way it looked this morning. i’ll keep you posted as to the date the snow has completely disappeared.
peter b
Peter, wonderful information. I suspected but did not know that the technique had a broader currency around the Lake. With that insight, I will watch the swallow also.
As to Jack, it may be that he watched the swallow on drives into Nelson from Kaslo; it also might be that there is more than one spot worth watching on the mountains around the Lake.