Careful studies of silt prove beyond doubt that its primal cause is the removal of the forest cover, such as underbrush, weeds, and grasses, along the streams, which allows the rainfall to run off rapidly. The grazing over these areas by sheep and goats not only exhausts this forest cover, but from the cutting up of the soil and the loosening effect of the thousands of tiny hoofs, the erosive action of the rain becomes disastrous. The wash of the hills and mountain-sides carries with it into the streams tons and tons of silt to fill up the dams and beds of the streams, as well as working irreparable injury to the comparatively thin soil covering the mountains.
On this national forest the watershed on the eastern side all runs into streams which eventually reach the Roosevelt Dam; on the western slope the water runs unused to the Gulf of California. So the National Reclamation Service, charged with the building and maintenance of these huge reservoirs, said to the Forest Service: "The watershed of the Roosevelt Dam must be protected from over-grazing, so that the forest cover may be preserved, and the deposit of silt reduced to the very lowest possible percentage."
THE SAME HILLSIDE AFTER TWO YEARS OF CAREFUL AND SYSTEMATIC GRAZING
The Forest Service whose duty it was under the law to protect and preserve, not only the timber of the mountains, but the water supply as well, had no alternative but to say to the sheep and goat men using this area: "You cannot longer graze sheep or goats upon the eastern side of this forest, but may do so on the western slope." But since cattle do much less damage than sheep, in order that the grazing may not go entirely unused, the Service allows cattle to graze there in such numbers as will not injure the watershed.
Naturally the sheep owners set up a cry that could be heard from Dan to Beersheba. But an analysis of the situation shows that while some fifty individual sheep men, owning probably 100,000 sheep valued at about $300,000, were forced to rearrange their business to meet the new conditions, their loss was overwhelmingly offset by the benefit to the entire population of the Salt River valley, a population to-day of not fewer than 50,000 people, every soul of whom is absolutely dependent upon the agricultural lands of the valley for a living; these lands consisting of more than 100,000 acres, valued at an average of sixty dollars an acre, already under cultivation, with 150,000 acres more ready to be cultivated the instant the Roosevelt Dam is finished.
Irrigation Revolutionized by National Forestry
Surely such conditions fully justify the Forest Service in its course of pursuing the greatest good for the greatest number. In Colorado a small number of stock men, principally cattle owners, aided and abetted by a few political malcontents, have attempted to discredit the Forest Service, but no one has heard a word against the Service from the thousands of contented irrigationists, who, with countless acres to be watered by more than 12,000 miles of irrigation ditches, see their source of water supply amply protected, and realize that already the supply has increased and the flow is more regular than it has been in the past.
In the great Kern River district about Bakersfield in southern California, a careful measurement shows that since the restrictions on grazing in the mountains at the heads of the streams, together with the almost complete absence of forest fires, the flow of water in the great canal system has become fully twenty per cent. greater in volume than ever before. And so one could go on without end, if necessary, for all over the West are smaller or larger areas wholly dependent upon the rivers and streams for their water supply, and to them the Forest Service guarantees full protection for their lands and homes.