ue in this country and perhaps the world, a treasure that the public
is presently defending against other, newer, subtler threats than mere
damming or encroachment.

A reservoir above Seneca clearly could not mean that sort of thing. It
would be a useful lake, but devoid of the changeless tone of the
Potomac as it flows there now. The reservoir's proper functioning would
require fluctuations in its level, with occasional ugliness at the
shoreline, and if it would permit a great deal of happy water-skiing and
flat-water fishing, the same opportunities are going to be available to
Washingtonians in the nearby estuary when it is suitably cleaned up,
even though the section immediately adjacent to the metropolis may take
a good while to bring up to swimming standards.

In terms of the overall good of the people of the metropolis and the
Basin and the country, the water situation at Washington now and during
the near future hardly bears a desperate enough aspect to warrant the
sacrifice of much of the main flowing river to a reservoir which, like
the freshwater estuary, could not be meshed with upstream needs but
would serve only the urban areas at and below the Fall Line. Conceivably
at some future time, if technology should renege on its promise to bring
forth good new alternatives, and population pressures continue to grow,
the city may badly need a reservoir there. It is a uniquely valuable
site. For that reason, we repeat our Interim proposal that the reservoir
site, minimally defined, be preserved against the mass encroachment with
which it is imminently threatened, and be utilized principally as part
of a major park complex protecting the river and its shores. To defer
irreversible decisions and to leave them as much as possible to future
generations whose conditions of life and desires we cannot predict with
accuracy, can be a principal way of maintaining freedom of choice.

In the category of reservoirs, at the other end of the spectrum are the
comparatively small headwater dams that the Soil Conservation Service
has been designing and supervising for three decades in authorized
watersheds throughout the country. These structures can serve several
functions and can furnish for small watershed areas and small centers of
population many of the benefits that the Corps of Engineers and Bureau
of Reclamation dams furnish for large areas. On their own scale, they
are vulnerable to some of the same objections that are aim