BULLETIN 82 . 
76 
alike suffer changes on entering the plains, and their return waters, as 
represented by the Platte river below the mouth of the Poudre, indicate 
that the changes suffered by them are, in all essential particulars, the 
same. 
54. These mountain waters are interesting and worthy of fuller and 
more detailed study than is proper to devote to them in this place. 
Therefore the discussion of them will be omitted, except one feature of 
the Clear Creek sample. Clear Creek presents an instance of a stream 
whose waters are laden with the mud and slimes from many mills, and 
whose waters are also used for irrigation. The sample analyzed was 
taken from an irrigation ditch. A full and careful analysis was made 
of it, a fuller and more careful one than would probably have been made in 
the case of a legal controversy, and yet it shows nothing that can be in¬ 
terpreted as a serious pollution of the water. The essential character¬ 
istics of a pure mountain water have scarcely been modified in the 
least. The purest mountain water in any of these streams carried 2.6 
grains per imperial gallon, Poudre river water, sample taken July 30, 
1902. The sample of water taken from Clear Creek, a stream which 
drains a section of country with a population of at least 25,000 souls, and 
receives indefinite quantities of mine water, and the refuse from twenty 
odd mills, carries less than eight grains to the imperial gallon, an in¬ 
crease which is less than that caused by a flow of a few miles (four to 
eight) in the plains section. Of the heavy metals, salts of which we 
might expect to find in this water, due to oxidation of the ores treated 
in the mills, we find none, a trace of zinc oxid, 0.0157 grain in each im¬ 
perial gallon, excepted. 
55. The suspended matter in our streams and ditches was found to 
be very much less than was expected, even in time of flood, due to heavy 
rains in the lower and, largely soil covered sections of the mountains, 
or in the foothills. The water, at the time the first sample given in the 
text was taken, corresponded to the colloquial expression, “as thick 
as mud.” The season was one of high water, when the usual flow is 
1,200 second-feet, due to the melting of the snow, but at this time it was 
ten times as great, or 12,000 second-feet. The rain fell in a hilly section 
and the fall of the river being great, we had conditions favorable to the 
tearing loose of soil, rocks and other debris. The crest of the flood had 
not passed at the time the sample was taken, and the amount of sus¬ 
pended matter in this sample probably represents the maximum that we 
may expect to find in this stream at any time. The amount of sediment 
equalled 3 tons per acre-foot of water. The aggregate amount of sediment 
carried by such a flow, 12,000 second-feet, laden as this was, is not far 
from 2,800 tons per hour, all of which, it is true, must sooner or later be 
deposited somewhere, and in considering this as a source of fertility we 
permit the impression of this big aggregate, and the fact that it is de¬ 
posited somewhere, to lead us to form too high an estimate of its actual 
available amount, and we at the same time assume that it is feasible to 
apply it to the land. If it were feasible and we applied two acre-feet of 
it to an acre we would add six tons of this suspended matter to the acre. 
This would, if spread evenly over the surface of the acre, fopm a coat¬ 
ing less than 0.04 of an inch in thickness, or twenty-five such floodiligs 
would, under very favorable conditions, furnish a dressing of this sedi¬ 
ment one inch in thickness. This would, of course, if rich in plant food, 
be a very desirable addition to the acre of land. There are, on the other 
hand, several considerations to be weighed before we set this gain down 
as an easily attainable fact. It is not a fact that we can apply this 
muddy water to our land when it is in the river, and the occasions when 
it is in the river are very seldom; this one scarcely having been equalled 
since the occupancy of this valley by the white man, except once, when 
it was due to the breaking of a dam. The facts on which the assumed 
supply of sediment is based, are wholly exceptional. But if we grant 
the supply, the question of value is an open one, and here, as in the 
question of quantity, we permit our judgment to be imposed upon. In 
that case the large total, and the fact that it is deposited, leads us to the 
