REPORT OF COMMISSIONER OF FISH AND FISHERIES. 141 
duction of species not native to them. The importance of these studies 
was much increased by the fact that a new hatching station for the 
“Salmonide was about to be established in the vicinity of Leadville, 
Colo., a site for the same having already been selected. In Colorado 
the Be iiiations had reference to four river basins, and were naturally 
confined for the most part to their upper 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; the Rio Grande, flowing directly into the Gulf 
of Mexico; and the Colorado, flowing into the Gulf of California. In 
Utah, in addition to the Colorado River, 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 somuch 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 rare 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, but during the summer and fall they are more or less confined to 
the mountains or the cafions. After reachin ¢ 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 Rivers have been almost ruined as trout streams by mining 
operations. Dr. Jordan says: 
In the progress of settlement of the valleys of the Colorado the streams have 
become more and more largely used for irrigation. Below the mouth 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 being turned 
into these ditches. Much of this water is consumed by the arid land and its vege- 
tation; the rest seeps back, turbid and yellow, into the bed of the stream, to be again 
intercepted assoon 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 fies Pa in Cotas and Utah aaa the summer of 1889, with 
an account of the fishes found in each of the river basins examined. By Dav a Starr 
Jordan. Bull, U. 8. Fish Comm., 1x, for 1889, pp. 1-40, pl. 1-v. 
