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. 

 Ail 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. Kalph 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 free 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 1^ 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 in summer. 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 volcanic mountains. The current is sluggish, and, according 

 to Mr. Dinsmore, the fall is so slight that it would be a comparatively 

 easy matter in tunes of ordinary flow to travel by canoe the entire 

 distance from the lake to the southern boundary of the park. 



