More and more often lately in such cases, a combination of some passive protection with the small headwater dams that "catch the water where it falls" and soil conservation measures to protect the 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 Savage River reservoir, finished in 1950, has cut down flooding notably in that area, and a dam at Bloomington above Westernport, already authorized by Congress, will relieve it still more, as well as fitting into the complex clean-up task along the North Branch and furnishing water for local and Washington use.