av4 FORESTS, RESERVOIRS, AND STREAM FLOW 
tionable than one is led in these later days to believe. Has it not 
from the beginning been one of the most beneficent operations of 
Nature? Are not the richest lands in the world—the river bottoms 
and deltas—built up in this way? To a very great extent the irrigated 
lands of the West are composed entirely of the débris from the moun- 
tains and the bad lands. Even to-day this tribute from the highlands 
is of great value. The periodic enrichment of the Ohio bottom lands 
and similar tracts in hundreds of other places, is of the highest 
economic importance. The soil-laden waters of irrigation in the 
spring, though sometimes injurious to the growing crop for the time 
being, are, on the whole, extremely beneficial. The damage from 
sediment is not in its injury to the lands ordinarily, ‘but to ditches, 
canals, reservoirs and similar works. On the whole, it is, and always 
has been, a benefit to the lowlands. Even that portion carried out 
to sea builds up deltas and surely, though slowly, extends the habitable 
area of the globe. Not alone in the resources of water and timber, 
but in the perpetual renewal of soil as well, has the valley said to the 
mountains throughout the world’s history: “I will lift up mine eyes 
unto the hills from whence cometh my help.” 
Sediment of this character, except when accompanied by alkaline 
salts or other similar ingredients, is not injurious to domestic supply. 
The water of the Missouri River is one of the healthiest drinking 
waters in the world in spite of the fact that it is one of the muddiest.* 
The proportion of soil wash that comes from cultivated fields is 
really very small compared with the enormous total that the rivers 
carry away. Heavy rains undoubtedly wash farm soils a great deal, 
but this erosion is in large part a transfer from one spot to another 
and not an absolute loss. The history of the old Ohio Canal reser- 
voirs indicates very little filling in the 66 years that they have 
been in existence. According to the Chief Engineer of the Ohio 
State Board of Public Works, it is scarcely appreciable in some of 
the reservoirs and in none does it amount to as much as 6 in., or gig 
in. per year from the tributary water-shed. Yet these reservoirs are 
surrounded by rich agricultural lands. The silt observations on the 
Ohio in 1879 indicate only a little more than ;1, in. over the entire 
water-shed; but this, it is true, was a year of light rains. 
*The late J. B. Johnson, M. Am. Soc. C. E., used to say, in extolling the vir- 
tues of Missouri River water, that it was the most perfectly filtered ae in the 
world; with this difference, however, that in the ordinary case water is run through 
the filter, but here the filter is run through the water. 
