Herein lie numbers that characterize Kootenay Lake. Various sources differ slightly in the values offered, so this information should be viewed as tentative. Some of the variability might result from whether a author included the West Arm in the measurements or not. This information is expected to undergo refinement and expansion.
Also available is a Chronology of the Lake.
Kootenay Lake bears a vague resemblance to a bow and arrow with the Main Lake being the bow, and the West Arm being the arrow. The Purcell Mountains lie to the east of the Main Lake, and the Selkirk Mountains lie to the west.
Altitude (above sea level): 532 m; seasonal variability, ~3 m.
Farthest southern latitude is 49°15’ north (Kootenay Landing).
Farthest northern latitude is 50°11’ north (Argenta).
Farthest eastern longitude is 115°39’ west (Kuskanook).
Farthest western longitude is 117°17’ west (Nelson).
Dimensions of the Main Lake
Length (straight line): 104 km from north to south.
Length (along centre line): 107 km for a boat going down the Lake.
Width: average, 3.8 km; variable from 1.7 km to 5 km.
Depth: average, 94 m; maximum, 150 m.
Surface Area: 390 km².
Volume: 37 km³.
Dimensions of the West Arm
Length (along the channel): 30 km for a boat to travel between
the Balfour dolphin and Nelson’s Orange Bridge.
Width of the West Arm: average .8 km (a guess),
variable from 0.1 km (Fraser Narrows)
to 1.4 km (Crescent Bay and Sunshine Bay)
Depth: average, 10 m (a guess), maximum, 47 m.
Area: 24 km² (a guess)
Slope: the Lake level drops ~15 cm between Balfour and Nelson.
Flow of water
Annual flow through the Lake averages about 25 km³ supplied by:
Kootenay River flowing in at the south end of the Main Lake, 80%;
Duncan River flowing in at the north end of the Main Lake, 10%;
Smaller rivers (Kaslo) and myriad big and small creeks. 10%.
Average residence time for water in the Lake
= (lake volume)/(volumetric flow rate)
= (37 km3)/(25 km3 year-1)
= ~1.5 years.
So, on average it takes about 1½ years for water to pass through the Lake. This is an interesting number in that the Lake probably completely overturns one or two times a year (in the spring and fall). Consequently, it is likely that all the water is replaced in the Lake over a period of a few years—it is unlikely that much of the bottom water in the Main Lake remains stagnant there for a long time. Likely, there is a difference between the residence times for the North and South Arms with the time being longer than average in the north and shorter in the south. The residence time for water in the West Arm is short, probably three or four days.
The higher adjacent mountains in the Selkirks and Purcells ascend about 2200 m above the Lake’s surface. (I have been hiking on Kokanee glacier above 2730 m at midday and swimming in the Lake at 532 m late that afternoon).
The nature of the forest surrounding Kootenay Lake changes with altitude:
532m (Lake level) to 1450m: Interior Cedar Hemlock zone.
1450m to 1950m: Englemann Spruce-Subalpine Fir zone.
1950m to 2600m: Englemann Spruce-Subalpine Fir parkland zone (previous link).
2600m and up: Alpine tundra zone.
The links, above, open a window to Selkirk College and Derek Marcoux’s discussion of the zone using the biogeoclimactic ecosystem classification in British Columbia.
The following applies to Nelson. To one extent or another, it characterizes the region, with the caveat that many things vary with altitude. Some of this data was provided by Discover Nelson.
|AVE. TEMP |
The population within about 2½ km of the lakeshore is about 19,700 people. This is divided between the Lake’s arms roughly as follows: West, about 14,300 of which most live in Nelson (9300), North, about 2900, of which many live in Kaslo (1000), South, about 2500.
The population within about 25 km of the Lake (ten times the above distance) increases by about 8000 to about 27,700, mainly because it now includes people living along the Kootenay River, both upstream of the Lake, 5500 with most in Creston (4800), and downstream, 2500.
These numbers were based upon Stats Canada for the region, and an RDCK map showing the various referenced areas. For the West Arm, I took 2/3 of both Areas F and E, plus Nelson. For the North Arm, I took Area D plus Riondel (400). For the South Arm, I took Area A minus Riondel. Upstream is Creston plus half of Area C; downstream is the remaining 1/3 of Areas E and F. The numbers were then rounded to the nearest 100. The numbers increase if one were to consider farther out along the river in either direction.
Vancouver is about 660 km from Nelson (at the West end of the West Arm). The track takes one over six mountain passes: Alison (1342 m), Sunday (1282 m), Rickter (682 m), Anarchist (1234 m), Eholt (1028 m), Paulson (1535 m). Calgary is about 620 km from Nelson. The number of passes depends upon the route. A typical route from Calgary might involve Crowsnest Pass (1396 m), Moyie Summit (997 m), Kootenay Pass (1774 m), and Apex (942 m), but other routes have other passes. These numbers are based upon Neil Roughley’s site.
What do I care about
numbers? I am a bird.