Using these flows and a head of 80 feet indicates power
possibilities of 12,400 ‘horse-power at ordinary minimum
flow, or 18,500 horse-power at ordinary six months flow.

Power Markets.—Mineral deposits, particularly copper
ores, in the neighbourhood of the Coppermine River offer
the only potential markets for power as far as is known at

YuKON River DRAINAGE

The Yukon River has a total drainage area of 360,000
square miles, of which 160,000 square miles are in Canadian
territory and 200,000 square miles in the United States
territory of Alaska. The Yukon is formed by the junction
of the Lewes and Pelly Rivers at Fort Selkirk. It flows
for a distance of about 250 miles, then crosses the Inter-
national Boundary into Alaska, continuing for another
1,150 miles to empty into Bering Sea. The river, having
cut for itself a relatively uniform gradient, is navigable
throughout its course and also up its tributary, the Lewes,
as far as Whitehorse thus providing an ‘unimpeded water-
way of over 1,600 miles. The same gradient charac-
teristics are found on the tributaries except in their
uppermost courses where slopes are steep as they descend
from the mountains. The principal tributaries which join
the Yukon in Canadian territory are the Lewes, Pelly, White,
Stewart, Klondike, and Fortymile Rivers. The Porcupine
River, another tributary, rises in Canada and flows across
the boundary to join the Yukon at Fort Yukon in Alaska.

Water Supply.—Water supply in the Yukon River
Drainage is governed by light precipitation, extremes of
temperature, permanently frozen subsoil and scarcity of
lakes. Light precipitation in the Yukon Valley is indicated
by records kept at Whitehorse and Dawson showing average
annual precipitation of 12-6 inches and 11-4 inches respec-
tively. In the higher altitudes, at river sources in the
mountains, precipitation is probably higher but records
are not available. The variation in the range of temperature
is great, averaging about 142 degrees, The maximum
temperature recorded at Dawson is 92 degrees above and
the minimum 68 degrees below zero. The few lakes which
exist in the watershed are found within or close to the
mountains and have a relatively small effect in regulating
river flows. :

The only continuous records of flow available of the
Yukon River are those obtained for a three-year period,
1911 to 1913, inclusive, at Eagle, Alaska, by the United
States Geological Survey. At Eagle, which is about 15
miles downstream from the International Boundary, the
drainage area is estimated at 122,000 square thiles. The
records indicated a minimum monthly mean flow of 11,000
c.f.s. in March, a maximum monthly mean flow of 199,000
c.f.s. in June, 1913, and a mean flow for the three-year
period of 73,200 c.f.s.

Stations were established in 1944 on the Teslin River
at the Alaska Highway crossing, on the Lewes River at

3681— 63

Whitehorse, and on the Yukon River at Dawson. In
1945, stations were established on the Klondike River (South
Fork) near Dawson, on the Stewart River at Mayo, on the
Mayo River at Minto Bridge, and on the McQuesten
River at Haggart.

Power Resources.—The only water-power development
now known to exist in the Yukon Drainage in Canada is
that of the Yukon Consolidated Gold Corporation on the
North Fork of the Klondike River, 26 miles from Dawson.
This plant, operating under a head of 212 feet, has an
installation comprising three 5,000-horsepower turbines,
each connected to a 3,000-kv.a. electric generator. Power
is used principally for the operation of gold dredges and of
pumps in stripping and thawing operations, and in the
company’s machine shops in the Dawson area. A small
amount of power is sold in bulk to the Dawson Electric
Light and Power Company Limited, for distribution in
the City of Dawson.

The Yukon River watershed in Canada, although large,
is lacking in major water-power possibilities. This is due
to the fact that concentrations of head in the form of falls
or rapids are confined, for the most part, to the mountain
sources of the various tributaries. Gradients are even on
the Yukon itself and throughout the greater part of the
tributary system. Due also to the perpetually frozen
subsoil and the low winter temperatures, river flows are
very low in the winter period and probably cease altogether
on some of the smaller tributaries. Reconnaissance investi-
gatians made by engineers of the Dominion Water and
Power Bureau on several tributaries of the Yukon revealed
power possibilities of moderate amount on the Lewes
River near Whitehorse and on the Stewart and its tributary,
the Mayo, in the vicinity of the Mayo mining area.

On the Lewes River, about four miles upstream from
Whitehorse, there is a descent of 30 feet in a distance of
about 3,500 feet through the narrow rocky defile of Miles
Canyon. By the construction of a dam, it is estimated
that a head of 50 feet could be secured and a power capacity

of about 1,800 horsepower would be dependable during
the low months of the year.

On Stewart River at Fraser Falls about 200 miles from
the mouth and 40 miles by river above Mayo, investigations
indicated that by the construction of a dam 60 feet high
above the falls a head of 80 feet could be secured. Under
assumed conditions of flow, the capacity of the site is
estimated at 7,300 horse-power at ordinary minimum flow,
or 21,800 horse-power at ordinary six months flow.

The Mayo River falls about 300 feet between Mayo
Lake and the Stewart River. Investigations indicated the
possibility of developing a head of 250 feet at one site
which would yield an estimated 2,400 horse-power at
ordinary minimum flow, or 7,200 horse-power at ordinary
six months flow. With storage in Mayo Lake, a dependable
capacity of 14,100 horse-power might be secured.

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