That it is still much too high in many parts of the upper Basin does not require elaborate instruments to detect, but only a nose and a pair of eyes. A very few industries and towns are still dumping raw wastes, and many of the others need better and bigger sewers and treatment plants or better operation of the plants they have. Sewage collection systems are sometimes of the old-fashioned combined type, like Cumberland's--and, as we shall see, like Washington's--which have to carry storm runoff as well as wastes, and overflow during rainy periods, releasing heavy pollution without treatment. But even separate sanitary sewers are often overloaded by having to serve greater populations than they were designed for, which means that their escape valves may leak raw sewage more or less continuously into surface watercourses and that the quality of treatment given the sewage that does reach the treatment plant signifies less than it ought to. Antiquated or overloaded treatment plants cause much trouble. Old primary plants too small for present populations often remove only about a third or less of the organic material, but by their very existence they tend to lull communities into a false conviction that they are doing their part toward clean rivers. Tiny plants of the sort authorized locally for new leapfrog subdivisions and vacation colonies are usually doomed to restricted efficiency by their very size. These often are underdesigned even for initial loads, let alone for the growth that comes later, and most of them are poorly run. This question of operation is crucial. A new, well-designed, expensive plant in slovenly or inexpert hands--a frequent paradox--can put out a much greater waste load than a well-operated old one. The plant at Romney, West Virginia, on the lower South Branch, the best example of responsible operation in the Basin, is old, but because it is well run it usually achieves about 92 percent elimination of B.O.D. in comparison with the 75 percent or even less that some newer and more imposing plants can claim.