nal Law the States possess dominion over the beds of all
navigable streams within their borders,[358] but on account of the
servitude which Congress's power to regulate commerce imposes upon such
streams, they are practically unable, without the assent of Congress, to
utilize their prerogative for power development purposes. Sensing, no
doubt, that controlling power to this end must be attributed to some
government in the United States and that "in such matters there can be
no divided empire,"[359] the Court held, in 1913, in United States _v._
Chandler-Dunbar Co.,[360] that in constructing works for the improvement
of the navigability of a stream, Congress was entitled, as a part of a
general plan, to authorize the lease or sale of such excess water power
as might result from the conservation of the flow of the stream. "If the
primary purpose is legitimate," it said, "we can see no sound objection
to leasing any excess of power over the needs of the government. The
practice is not unusual in respect to similar public works constructed
by State governments."[361]

Congress's Jurisdiction Over Navigable Streams Today

Since the Chandler-Dunbar case the Court has come, in effect, to hold
that it will sustain any act of Congress which purports to be for the
improvement of navigation whatever other purposes it may also embody;
nor does the stream involved have to be one which is "navigable in its
natural state." Such, at least, seems to be the algebraic sum of its
holdings in Arizona _v._ California,[362] decided in 1931, and in the
United States _v._ Appalachian Electric Power Co.,[363] decided in 1940.
In the former the Court, speaking through Justice Brandeis, said that it
was not free to inquire into the motives "which induced members of
Congress to enact the Boulder Canyon Project Act," adding: "As the river
is navigable and the means which the Act provides are not unrelated to
the control of navigation, * * *, the erection and maintenance of such
dam and reservoir are clearly within the powers conferred upon Congress.
Whether the particular structures proposed are reasonably necessary, is
not for this Court to determine. * * * And the fact that purposes other
than navigation will also be served could not invalidate the exercise of
the authority conferred, even if those other purposes would not alone
have justified an exercise of congressional power."[364] And in the
Appalachian Electric Power case, the Court, abando