ful greenery. Cleanup
of pollution as complex as that evolved in the 20th century has to be
across the board.

[Illustration]

Barring a general philosophical revolution on the part of the American
people, the problem of junk and debris in our waters is likely to
continue and even to increase as people and their consumption of the
products of the economy maintain their geometric growth. Clean rivers in
themselves might deter a good many people from cluttering them thus, and
so might public education, stiff fines, and the provision of better
municipal pickup and dumping facilities. But mainly getting rid of such
detritus is probably going to be a matter of fairly continuous
gathering and disposal. On navigable waters like those of the upper
Potomac estuary, ingenious collection craft under the command of Army
Engineers are in prospect; elsewhere the job is likely to be more
old-fashioned and laborious.

For certain remaining pollution problems, no definite full technological
answers exist at present and the main hope must be to alleviate them as
much as possible while pressing a search for long-run answers. Some are
relatively restricted in their effects in the Potomac Basin so far,
though they have some drastic local effects and some long-run
implications. Certain industrial wastes not amenable to any presently
known form of treatment, such as tannery discharges at Petersburg, West
Virginia, and Williamsport, Maryland, are one example. So are the
noxious exudations of raw sewage and garbage from ships and pleasure
craft. Marinas themselves and the boats docked there can and must be
connected to waste collection systems. Laws can and should prohibit
discharges from watercraft in harbors and rivers. But until better means
of on-board waste treatment or retention than exist at present are
evolved and made mandatory, the multitudes of boats with standard toilet
facilities are going to keep on causing trouble.

Other sources of trouble without clear-cut present solutions are big
ones. Surface runoff from both cities and rural areas, as we have seen,
causes much pollution. In the country, soil conservation measures can
slow it somewhat and strain out some pollutants, and augmentation of
streams' flow can enhance their capacity to oxidize the wastes. But
neither of these seem likely to do much to ease the longrun buildup and
diffusion of persistent pollutants like pesticides, or to avert the
possibility of disastrous spil