REPORT OF COMMISSIONER OF FISH AND FISHERIES. 141 



duction of species not native to tliem. The iinpoitauce of these studies 

 was much increased by the fact that a new hatching station for the 

 iSahnonulw was about to be established in the vicinity of Leadville, 

 Colo., a site for the same having already been selected. In Colorado 

 the examinations had reference to four river basins, and were naturally 

 confined for the most part to their upj)er courses, although on three 

 of the rivers the work was extended beyond the limits of the State. 

 These river basins were as follows: The Platte and Arkansas, tributa- 

 ries of the Mississippi 5 the Eio Grande, flowing directly into the Gulf 

 of Mexico; and the Colorado, flowing into the Gulf of California. In 

 Utah, in addition to the Colorado Eiver, the Great Salt Lake and 

 Sevier Lake basins were examined. 



According to Dr. Jordan's report* of this expedition, most of the 

 streams of Colorado rise in springs in or above the mountain meadows, 

 while many have their origin in banks of snow, their waters being very 

 clear and cold. In their descent from the snow banks they are brawl- 

 ing and turbulent, often so much so as to be unfitted for fish life. In 

 their course through the mountain meadows the streams have usually 

 a gentle current, and lower down most of them pass to the valleys 

 through deep canons, which generally, however, present no obstacles 

 to the presence of trout, especially as vertical falls are very lare in 

 Colorado. In the valleys the water grows warmer, fine silt renders it 

 more or less turbid, and at last it becomes unfit for trout, and at the 

 same time suitable for suckers and chubs. During the colder temper- 

 ature of winter the trout extend their range somewhat down the val- 

 leys, l)ut during the summer and fall they are more or less confined to 

 the mountains or the caQons. After reaching the base of the mountains 

 the streams flow with little current over the ill- defined beds across the 

 plains. In some cases placer mining and stamp mills have filled the 

 waters of otherwise clear streams with yellow or red clay, rendering 

 them almost uninhabitable for trout. Parts of the Upper Arkansas and 

 Grand Kivers have been almost ruined as trout streams by mining 

 operations. Dr. Jordan says: 



In the progress of .sottlomeut of tho valleys of the Colorado the streams have 

 become more aud more largely used for irrigation. Below tho month of the canons 

 dam after dam and ditch after ditch turn off the water. In summer the beds of even 

 large rivers (as the Rio Grande) are left wholly dry, all of the water lieiug turned 

 into these ditches. Much of this water is consumed by tho arid land and its vege- 

 tation ; the rest seeps back, turl)i(l and yellow, into the lied of the stream, to be again 

 intercepted as soon as enough has accumulated to be worth taking. In some valleys, 

 as in the San Luis, in the dry season there is scarcely a drop of water in the river 

 bed that has not from one to ten times flowed over some field, while the beds of 

 many considerable streams (Rio la Jara, Rio Alamosa, etc.) are filled with dry clay 

 and dust. Great numbers of trout, in many cases thousands of them, pass into these 



* Report of explorations in Colorado and Utah during the summer of 1889, with 

 an account of the fislus found in each of the river basins examined. By David Starr 

 Jordan. Bull. U. S. Fish Comm., ix, for 1889, pp. 1-40, pi. i-v. 



