FISH-CULTURAL INVESTIGATIONS IN MONTANA AND WYOMING. 
9 
Drainage . — Tlie whole State of Montana and that portion of Wyoming 1 2 3 4 5 6 7 8 visited by us 
are drained entirely by the Columbia and the Missouri, the headwaters of those two great 
rivers having- their rise on the Great Continental Divide, near which our investigations 
were chiefly confined. By far the greater part of Montana, nearly all that portion 
lying east of the meridian of 112° 30', lies within the Missouri drainage area. In the 
northwest part of the State the divide lies more than a degree farther west, and in the 
southwest the Missouri drainage extends westward to the Idaho State line. The 
Missouri also drains all of northwest Wyoming excepting the southwest portion of 
the National Park and part of the region south of the Park. This part of Wyoming 
belongs to the Columbia River Basin, being drained directly by the Snake River and its 
tributaries. In general it may be said that the streams of the Missouri system flow in 
a northeast or northerly direction. Those tributary to Clarke Fork of the Columbia 
flow to the northwest, while the drainage into the Snake River or Lewis Fork of the 
Columbia is to the southwest. 
Nearly all of these rivers and creeks are, of course, swift mountain streams; most 
of them have their rise in small lakes of clear, cold water, high up in the mountains — 
lakes which as yet are difficult, of access and but little known. Many of these lakes 
are known, however, to be well supplied with trout, while others are wholly without 
any fish life whatever. From these mountain lakes the swiftly flowing, turbulent 
streams make their descent through rocky gorges and canons to the valleys below. 
Ordinarily the beds of the streams are very rocky, but now and then are found more 
quiet reaches where the streams have sand or gravel beds as they flow through small 
mountain meadows. Then, at other places, there are rapids and cascades, and in 
many of the streams are found considerable waterfalls. The best illustrations of this 
are in the numerous magnificent falls found in the streams flowing from the great 
volcanic plateau constituting the larger part of the Yellowstone National Park. As 
the streams leave this immense sheet of rhyolite, they do so in great falls, such as those 
of the Yellowstone, Gibbon, and Lewis rivers. Others of the same nature are to be 
found in the country lying to the east of the National Park in the Clarke Fork of the 
Yellowstone, and other streams of that region. These falls, of course, serve as more 
or less effective barriers to the distribution of fish, and as a result many of the moun- 
tain lakes, though of the most suitable character so far as temperature, purity, and 
abundance of food-supply are concerned, are wholly barren of fish life of any kind. 
The larger streams are, as a rule, less swift, and have more sandy and gravelly beds. 
There are few, if any, sluggish streams in this region, and all are clear unless contam- 
inated by mining operations. 
The following is a classified list of the waters examined: 
A. — Columbia River Basin. 
I. Clarice Fork : 
I. Clarice Fork — continued: 
1. Flathead River. 
2. Flathead Lake. 
3. Swan River. 
4. Depew Creek. 
5. Swan Lake. 
6. Post Creek. 
7. Mission Creek. 
8. Jocko River. 
9. Missoula River. 
10. Bitter Root River. 
11. Lolo Creek. 
12. Rattlesnake Creek. 
13. Hell Gate River. 
14. Big Blackfoot River. 
15. Little Blackfoot River. 
16. Deer Lodge River. 
