8 U. S. BUREAU OF FISHERIES. 
this arm he found the largest redthroat trout met with in the park, 
fine, clean, trim, vigorous fellows, not like those observed elsewhere. 
All suitable tributary creeks contain redthroat trout. The most 
notable creeks on the east side of the lake, enumerated from north to 
south, are: Pelican, Cub, Clear, Columbine, and Beaverdam Creeks. 
All contain native trout. Sylvan Lake, which discharges through 
Clear Creek in times of high water, contains a few trout. It is a 
beautiful mountain lake, clear and moderately cold. Ralph E. Clark 
said of Pelican Creek: 
One mile east of Yellowstone River outlet is Pelican stream, which rises in the cold 
snows of the mountains and empties its waters into the lake. Here you catch quan- 
tities of uncontaminated trout, large, beautiful, fat, and gamy, as iree from worms 
as the fresh cold waters they swim in are free from pollution. 
On the west side of the lake, named in the same order, are Bridge 
Creek, entering Bridge Bay; Arnica Creek, an affluent of the north- 
west side of the Thumb; Solution Creek, a small, narrow stream, with 
lava bottom and grassy banks bordered with willows, the outlet of 
Riddle Lake, sometimes going dry. Riddle Lake, so called because 
of the former mystery of its outlet, is a clear pond of roundish outline, 
about 14 miles in diameter, about whose outlet are numerous lily 
pads and other plants. Its shores are shallow, and its bottom is 
chiefly of lava gravel. The temperature is about 50° F. Trout are 
numerous. 
Near West Thumb is another small, deep-set lake, named Duck 
Lake, which has no outlet. It formerly contained no trout, but red- 
throat trout and landlocked salmon were planted in it. Redthroat 
trout now appear to be abundant, but landlocked salmon have never 
been observed. However, the senior author found good-sized Loch 
Leven trout common in 1919. 
Grouse and Chipmunk Creeks enter opposite sides of the southern 
end of the South Arm. Besides these there are numerous unnamed 
creeks, some of which go dry insummer. One, however, flowing into 
Flat Mountain Arm, was found by the senior author on July 17, 1919, 
to contain more water than many of the other creeks around the lake, 
probably never going dry. A creek that will flow as did this one 
during a period of drought, with the lake level one-third lower than 
ever before known, must be permanent. The creek, unnamed on the 
available maps, clear and cold, with beautiful green, grassy banks 
with trees here and there, meanders to an, extraordinary degree 
through a broad, open valley, flowing over a gravelly bed, now with 
riffles, now with deep holes, making a charming trout brook. At its 
mouth is a flat much frequented by elk. This creek was found to 
contain numerous trout of season’s hatch; some 3 to 5 inches long 
of the previous season; and older fish up to 12 inches in length. 
YELLOWSTONE RIVER ABOVE THE LAKE. 
Above the lake the Yellowstone River winds through marshy 
meadows, between wooded hills, behind which are the rugged peaks 
of high voleanic mountains. The current is sluggish, and, according 
to Mr. Dinsmore, the fall is so slight that it would be a comparatively 
easy matter in times of ordinary flow to travel by canoe the entire 
distance from the lake to the southern boundary of the park. 
