FISHES OF COLORADO II 



miles just north of the New Mexico boundary is drained by the 

 Cimarron River. This stream joins the Arkansas in Oklahoma. 

 In the present paper it is considered a part of the Arkansas system. 



2. Rio Grande. — The San Luis Valley is the only portion of 

 Colorado east of the Continental Divide which is not a part of the 

 Mississippi drainage, the Rio Grande emptying into the Gulf of Mexico. 

 In Colorado this river does not fall below the 7,000-foot contour, yet 

 flowing as it does through a fairly level mountain valley the lower 

 half of the stream is for the most part sluggish and has a clay bottom. 

 From its source on the east slope of the Continental Divide in San 

 Juan County the Rio Grande descends 2,000 feet in the first twenty- 

 five miles, and 1,200 feet in the next fifty, so that above Del Norte 

 it is a mountain torrent flowing over large rocks and bowlders. 



3. The Colorado River System. — West of the Continental Divide 

 all of the streams in Colorado flow into the Colorado River, which 

 empties into the Gulf of California. Western Colorado is divided 

 into several rather isolated valleys. Five independent streams have 

 their headwaters in this portion of the state. Starting with the most 

 northern these streams are: the Yampa River, the White River, the 

 Grand River, Rio Dolores and the San Juan River. Each of these 

 joins the Colorado River shortly after leaving the state, most of them 

 within a hundred miles of the Colorado line. The Grand River and 

 its southern tributary, the Gunnison, together with the Rio Dolores, 

 which flows into the Grand in eastern Utah, drain the central half of 

 western Colorado. The Grand River proper rises in the extreme 

 northern part of Middle Park. Flowing in a southwesterly direction, 

 it leaves Middle Park through Gore Canyon and continues as a tur- 

 bulent mountain stream to beyond Glenwood Springs. At Grand 

 Junction, where it is still a vigorous stream, it is joined by the Gun- 

 nison River. Beyond this confluence the Grand becomes a wider, 

 slower river, continuing to the state line as a typical plains stream. 

 The Gunnison, although flowing through sage-brush plains for some 

 distance before joining the Grand, is a rapidly moving river even at 

 Grand Junction. The mountain streams that constitute the head- 

 waters of the Gunnison, on the west slope of the Continental Divide 



