The forests are natural reservoirs. By restraining the streams in flood
and replenishing them in drought they make possible the use of waters
otherwise wasted. They prevent the soil from washing, and so protect the
storage reservoirs from filling up with silt. Forest conservation is
therefore an essential condition of water conservation.

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