e watershed lands
above the reservoirs, has proved to be a better solution. This is what
has been done in the Rock Creek watershed in the District of Columbia
and Montgomery County, Md., and its value was shown during the heavy
rains of September 1966. Here stream valley parks have given passive
protection for a long tune, though the popularity and heavy use of the
parks have caused a big investment in picnic areas, playgrounds, and
other facilities, which themselves have often suffered expensive flood
damages. As a result of long effort by a watershed association, two S.
C. S. dams had been finished shortly before the September flood at the
only useful sites on the creek's upper branches that rapidly spreading
residential development had left available. They kept runoff from the
big sudden rains entirely in hand in Maryland and reduced damage in the
Federal park in the District to a point far below what it would have
been without them.

Ideally, of course, such planning should be done before heavy
development, and a pilot urban watershed program of this sort is being
undertaken in the Pohick Creek basin on the metropolitan fringe in
Fairfax County, Virginia. With freedom to locate necessary structures in
the right places and to protect them against silt and ruinous runoff by
requiring good land treatment and a sensible distribution of buildings,
pavements, and wooded or grassy open space, planners there ought to get
good flood protection while preserving a pretty valley and stream for
the people who will be living in the neighborhood. From any number of
standpoints, this is vastly preferable to the more usual traditional
procedure of letting growth run wild and then trying to cope with
trouble when it comes up.

The headwater dams are equally effective in reducing flood damages in
small rural watersheds where losses warrant their installation. But even
on a massive scale of installation they have little influence on
downstream flooding along the main rivers. In such places--at
Cumberland, Petersburg, and the Washington metropolis, and at certain
other river towns where less damage occurs--other measures are going to
have to be selected and applied in each individual case according to
costs and benefits, physical possibilities, and the best interests of
the region.

Cumberland and the lesser damage centers on the North Branch are
scheduled for the classic engineering solution of big dams upstream. The
existing Savag