64 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
The following analysis of the Eio Grande water is given in the same bulletin, but 
it is not stated just when or where the sample was obtained : 
Analysis of Eio Grande water. 
Grains per 
gallon. 
Suspended matter (inorganic) 
98. 65 
Total residue in clear water 
40. 65 
Organic and volatile matter 
5.05 
Total soluble matter 
29. 15 
Lime 
4. 65 
Sulphuric acid (anhydrous) 
3. 23 
Alkaline chlorides 
Silica, iron, and alumina not determined 
1.77 
This water when collected was very muddy, hence the large amount of suspended 
inorganic matter. The area of the Eio Grande basin is about 240,000 square miles. 
The only tributaries of any size from the United States are the Pecos and Devil rivers. 
The Pecos rises in New Mexico and runs approximately due south, then southeast for 
about 800 miles, the greater part of which distance is through an arid table land nearly 
destitute of timber. Devil Eiver is a much smaller stream which empties into the Eio 
Grande several miles below the mouth of the Pecos, and which is said to be a much 
clearer, colder stream than the other rivers of Texas. The most important affluents 
which the Eio Grande receives from the Mexican side are the Eio de las Conchas, Eio 
Salado, Eio Sabinas, and Eio San J uan. Of these the Conchas is by far the largest, 
and is about 300 miles long. • 
Beginning as far up the Eio Grande as Wagonwheel Gap and Del Norte in Colo- 
rado, and extending down the stream and on its principal tributaries, are found 
numerous irrigation ditches, many of which are of enormous size. The demands of 
these ditches are so great that during the season of growing crops the Eio Grande is 
almost wiped out of existence and is left in many portions of its course only as a wide 
sandy river bed with but little running water. This very seriously affects the fishes. 
At Del Norte, Colo., in 1889, I was told that great quantities of trout and other 
fishes run out into the irrigating ditches and are left to die as the water spreads over 
the fields. Unless these ditches are screened or some effective means taken to prevent 
fish from entering them, it will not be many years before the trout of the Upper Eio 
Grande will be a thing of the past. Suckers and all other species that are more or 
less migratory will also be seriously affected by the present irrigation methods. 
In Chihuahua and the other Mexican states lying along the Eio Grande, and to 
some extent in the Llano Estacado and the Trans-Pecos region, are found some small 
isolated bodies of water which have at present no outlet to the sea; most notable 
among these is Lake Guzman in the northern part of Chihuahua, into which flow the 
Eio Mimbres and Eio Janos. While these lakes and sinks have at present no con- 
nection with the Eio Grande, they probably all did have at one time and properly 
belong to the basin of that river. 
Summing up the climatic and hydrographic features of Texas and the Eio Grande 
basin, the conditions which are most characteristic and which are most important in 
their bearing upon the fish life of that vast territory, are the following: The distri- 
bution of rainfall throughout the year is very irregular, resulting in periods of heavy 
rains and long seasons of drought; this results in periodic freshets which suddenly 
swell the streams to enormous proportions, to be followed by seasons of little rain when 
these great rivers dwindle to mere creeks, isolated stagnant pools, or in some cases 
