The forests alone cannot, however, fully regulate and conserve the waters of the arid region.  Great storage works are necessary to equalize the flow of streams and to save the flood waters.  Their construction has been conclusively shown to be an undertaking too vast for private effort.  Nor can it be best accomplished by the individual States acting alone.  Far-reaching interstate problems are involved; and the resources of single States would often be inadequate.  It is properly a national function, at least in some of its features.  It is as right for the National Government to make the streams and rivers of the arid region useful by engineering works for water storage as to make useful the rivers and harbors of the humid region by engineering works of another kind.  The storing of the floods in reservoirs at the headwaters of our rivers is but an enlargement of our present policy of river control, under which levees are built on the lower reaches of the same streams.

The Government should construct and maintain these reservoirs as it does other public works.  Where their purpose is to regulate the flow of streams, the water should be turned freely into the channels in the dry season to take the same course under the same laws as the natural flow.

The reclamation of the unsettled arid public lands presents a different problem.  Here it is not enough to regulate the flow of streams.  The object of the Government is to dispose of the land to settlers who will build homes upon it.  To accomplish this object water must be brought within their reach.

The pioneer settlers on the arid public domain chose their homes along streams from which they could themselves divert the water to reclaim their holdings.  Such opportunities are practically gone.  There remain, however, vast areas of public land which can be made available for homestead settlement, but only by reservoirs and main-line canals impracticable for private enterprise.  These irrigation works should be built by the National Government.  The lands reclaimed by them should be reserved by the Government for actual settlers, and the cost of construction should so far as possible be repaid by the land reclaimed.  The distribution of the water, the division of the streams among irrigators, should be left to the settlers themselves in conformity with State laws and without interference with those laws or with vested fights.  The policy of the National Government should be to aid irrigation in the several States and Territories in such manner as will enable the people in the local communities to help themselves, and as will stimulate needed reforms in the State laws and regulations governing irrigation.