The body of this report is an Interior Department document, couched wherever possible in untechnical language in the hope that it may find a wide lay readership. Necessary technical supporting material mainly has been or will be made available in separate form. The report examines environmental problems in the Potomac Basin and possible solutions for them. Its underlying emphasis is ecological, based in a conviction that man's own good is heavily dependent on the good of the earth in all its complexity. No one at this point in time, obviously, is going to be able to reconstitute the primeval Paleolithic world, nor would many people want to. The earth has changed with people in their long surge toward dominion over its ways and its creatures. But there is a difference between adaptive change and the degeneration that modern times are forcing on the earth men have always known. Growing millions of people are coming to consider that human beings' right to see and know woods and plains and mountains and streams and coasts in a cleanly and decent condition--whether primitive or adapted in one way or another to man's use--together with the communities of wild creatures that belong there, is quite as practical and urgent as their right to usable tap water or to a share in the Gross National Product. For upon the retention of these ancient realities future human sanity and wholeness may well depend. We who are responsible for this report believe that this point of view is going to gain enough strength and political acceptance to become one of the motive forces of this century. Already it has much power. Even though many established attitudes, laws, and practices are still firmly rooted in the old exploitative, often heroic urge to seize upon all resources and put them to use at whatever ultimate cost, disgust over pollution and the destruction of beautiful places is getting to be a political factor to be reckoned with at all levels of government. So is concern over man's lemminglike multiplication in numbers and the way his technology and his expansionism are gobbling up things quiet and graceful and eternal--things he needs. It seems certain that political "muscle" and respectability for the legitimate conservationist viewpoint is shaping up fast enough that it will be able to dissipate the worst threats--the grabbing and the spoiling, the ignorance and the archaic attitudes, the onward shove of brute technology for technology's own sake rather than for man's--before they have forced mankind on into the gray sterility of life that would be their ultimate effect.