itious connections of house sanitary sewers to the storm system,
breaks and leaks in sanitary sewers, and such things. Partly too they
seem to come from the fact that some sanitary sewers are having to carry
more sewage than they were designed to handle, so that their overflow
valves leak more or less constantly into the storm sewer system. The
capacity of sewage collection systems is related to planning. If a pipe
is laid down to a fringe area where county zoning maps indicate only
limited development is going to be permitted, its size is gauged to that
kind of development. But if the zoning is changed later and three times
as many houses are hooked up to the line as were originally envisioned,
trouble results. Rock Creek is heavily affected by such sewage, and the
chances are that the situation is much worse on many other urban
drainways, for their longstanding degradation or sheer disappearance
from view has lost them the alert defenders who watch over Rock Creek in
its pleasant valley.

Out of the storm sewers whether combined or separate, off of the roads
and streambanks and hillsides, down the urban tributaries or directly
overland into the estuary, comes still another big jolt of organic and
bacterial pollution every time there is a heavy rain. This is surface
runoff, the washings of the street and parks and sidewalks and rooftops.
Besides debris, it contains vast hordes of bacteria and many kinds of
organic oxygen-demanding substances, of which animal droppings are only
one easily definable example. Around a city the size of the Washington
metropolis, this runoff would constitute a worrisome pollution problem
even if the matter of sanitary wastes were thoroughly in control.

[Illustration]

Ships and large boats in the estuary, in accordance with an
unfortunately persistent nautical tradition, generally discharge toilet
wastes and garbage directly into the water on which they float. Some of
these are coastal or transoceanic vessels, both commercial and naval.
Many more belong to the fleet of pleasure boats which have been
increasing at Washington despite the water's unpleasant state to which
they add their bit, degrading the element that is supposed to provide
the enjoyment for which the boats were built. It is not a problem
limited to the Potomac estuary, but widespread these days and the focus
of much concern among public health and pollution control authorities,
conservationists, and the boat and marina ind