58 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
lake are being quite rapidly worn away by rough water, forming bluffs. The surface 
of the lake at one time was somewhat lower than at present; this is evident from the 
fact that on a shoal place on the east side (near the middle of section 14) stumps of 
trees are seen some 10 feet below the surface. The former outlet of the lake was into 
the outlet of Tsiltcoos Lake. A few years ago this outlet became closed by shifting 
sand, causing the water to rise in the lake at least 6 feet above its present level. A 
new outlet, a short distance to the east of the old one, was dug to Tsiltcoos Labe 
some four or five years ago. The new outlet was not only intended to lower the sur- 
face of the lake, but to afford a water power for a small sawmill. It has never been so 
used. The material through which the outlet was dug is a fine clay, so compact that 
it erodes very slowly. In the extreme ends of the arms of the lake are some tales 
and small areas of other water-plants. 
The surface of Whoahink Lake is about 15 to 20 feet above that of Tsiltcoos Lake, 
from which it is less than half a mile distant. The timber on the hills bordering the 
lake was nearly all destroyed by fire some sixty years ago. It is being replaced by a 
growth of fir, alder, hemlock, maple, rhododendron, huckleberry, and a vigorous growth 
of ferns. To the west and bordering the sand hills about half a mile distant from the 
lake are many bull pines. The shore was everywhere so snaggy that a seine could not 
be used and our collecting apparatus consisted only of gill nets and trot lines. This 
lake is reported as having very few fishes in it, and our experience confirms this view. 
The water is clear, though much less so than in the mountain lakes of Idaho; the 
depth is usually from 30 to 78 feet. The water is not very cold, as may be seen from 
the following recorded temperatures : 
Date. 
Hour. 
Tem- 
per- 
ature 
of air. 
Temperature of water. 
Sur- 
face. 
Depth. 
Bot- 
tom. 
1896. 
Oct. 18 
18 
19 
19 
19 
4.30 p.m. 
OP. 
63 
62*" 
Feet. 
54 
72 
30 
54 
66 
op. 
61 
56 
60 
61.5 
57 
9.30 a.ni. 
58 
61.5 
Tsiltcoos lake is larger and more irregular than Whoahink Lake. The main body 
of the lake is about 2 miles in extent from north to south, and 1 to 2 miles from east 
to west. It is also supplied with several arms, usually about a fourth of a mile wide 
and from £ to 1£ miles long and extending in different directions. Tsiltcoos Lake is 
comparatively shallow. In summer its greatest deptli is about 17 feet, its average 
depth being from 10 to 14 feet. During the rainy season the water is from 6 to 10 
feet deeper. The bottom is a soft, black mud, like that of Whoahink and Tahkenitch 
lakes. Except at a few intervals the shore is bordered by a rich growth of tules. In 
the shallow portions around the shore the tules extend into the lake about a fourth of 
a mile. There is also considerable swamp vegetation in and about the tules. The 
surrounding country is quite similar to that around Whoahink. On the east, and at 
one point on the south, are bluff's of a dark, compact sandstone of much older formation 
than the bluffs around Whoahink Lake. There are also two timbered islands in this 
lake, composed of this older sandstone; the larger is about half a mile long and about 
an eighth of a mile wide. That portion of the country bordering the lake on the south 
and southwest was not burnt over during the big fire of about sixty years ago. 
