46
Mean Temperature at Barkerville, 1888-1915 (Degrees F.)

June | July | Aug. | Sept. | Oct. | Nov. | Dec. | Year

19-2 | 26-1] 34:8] 44-4] 50-1] 54-4] 53-7] 45-5] 37-7] 25-3] 20-9 | 35-7

a NS | eee |e

The temperature rarely rises above 80 degrees or falls below —20
degrees and in some years these extremes are not reached,

Feb. | Mar. | April | May

Mean Precipitation at Barkerville, 1888-1923 (I nches)

Sept. | Oct.| Nov. | Dec. | Year
3-51 | 3-18 3-45 3:43 | 36-47

July
3-25

Feb. June Aug.

2-51

Mar.
2-40

April | May
2-11] 2-56

Jan.

3-37

3-49 3-21

The precipitation in 1908, the wettest recorded year, was 49-54
inches; the precipitation in 1896, the driest, was 20-61 inches. The
years 1917 to 1922 inclusive were exceptionally wet, the precipitation each
year being over 40 inches and averaging 43-35 inches. They were preceded
by a long series of relatively dry years interrupted by an occasional wet
year. In only four years during the period from 1888 to 1916 did the pre-
cipitation exceed 40 inches. The precipitation in 1923 was 36-68 inches or
very nearly the average for thirty-six years. The average winter’s snowfall
is 188 inches. It varies greatly from year to year. In the winter of 1904-05
it was only 97 inches; in the winters of 1916-17 it was 258-3 inches.

The water available for hydraulicking is mostly derived from the
levels above 4,500 feet, and, therefore, comes chiefly from melting snow.
The amount available in any season depends on the amount of snowfall
during the preceding winter, on the way in which the snow melts in spring
and early summer—whether gradually or rapidly—and on whether or not
it disappears largely by evaporation. Comparatively little melting of the
snow occurs during most winters, although thaws occasionally occur and
cause some increase in the run-off which is ordinarily very low during the
winter, especially at the higher levels. Below about 5,000 feet there is
some run-off during the winter because of the flow from springs, the temper-
ature of the ground water throughout the year being about 36 degrees F. or
practically the same as the mean annual temperature. In some years a
sufficient flow of water has been available on a few of the creeks to operate
water-wheels throughout the winter. Fairly extensive thaws, followed by
freezing temperatures, occasionally occur in March or April before the
usual time of opening of the hydraulic season and before preparations for
hydraulicking are completed. If the snowfall be heavy it is necessary to
clear the ditches to a depth of several feet; otherwise, the water is likely
to be dammed by the snow and to cause washouts in the ditch. If the
snowfall be light it is necessary merely to work the ditches ahead of the
water. The flood water in the spring lasts, as a rule, from three to six
weeks, but in some years only one or two weeks. The run-off gradually
decreases during the summer, and reaches a minimum for the summer