and
is well confined by abrupt banks. Opposite the old French Hill dump the
river is 500 feet wide, and at La Grange, from which place to its mouth
the grade is only a few feet to the mile, its width is 525 feet. Three
hundred yards below the town, opposite the Light claim, it widens to
750 feet. Down the stream from this point the hills recede for the
succeeding three or four miles, but subsequently form prominent banks
to the river. During high water, opposite the Light claim, at its
greatest width, its average depth was 10 feet* the centre of the
channel being 14 feet deep. When the La Grange Company commenced work,
in 1872, the bottom of the channel was a few feet deeper.
The Light claim was worked in 1873, and up to June 23,
1874, had discharged 720,086 cubic yards of gravel into the stream.
During the same period 975,064 cubic yards were dumped into the river
from the Kelly and French Hill properties. The results at the
expiration of 21 months were, that the channel opposite the Light claim
was filled up, the sluices were run out of grade, the river bed was
shoaled on all sides, the water of a formerly rapid stream straggled
over the accumulated debris with a barely perceptible motion, and it is
hardly necessary to add that the claim was closed.
The
spring freshets of 1875-76 were unusually severe, clearing the river at
the claim for its entire width and leaving a dump of over 11 feet along
its west bank. In the spring work was resumed, and 48,280 cubic yards
were moved in the Light claim and 212,346 cubic yards from French Hill,
which was a quarter of a mile upstream. By September the river was
filled up nearly its entire width to the height of the sluices, and the
water was confined to a strip 30 feet wide, discharging 1 foot deep
over a bar.
Exceptional Cases.—Where
a small amount of tailings is discharged into narrow and steep canons,
winter rains and spring freshets suffice to clean them out; but
