feed.

[Illustration]

Such additions are frequent for the next 45 miles or so downstream, as
the North Branch in its narrow valley swells into a mountain river with
the water of brooks and creeks flowing off ridges pocked with coal mines
old and new. The river and such tributaries sustain no aquatic life at
all among the discolored stones in their channels.

This mine-derived pollution has been much studied but is still not well
understood. Sulphuric acid is its most damaging component, but may be
accompanied by iron salts and other substances also leached from
materials in and around the vast coal beds of Appalachia. Some acid
entered the streams there naturally, before men ever touched the coal,
but it has increased to deadly proportions with widespread mining. It
issues from both surface strip mines and the old-fashioned underground
sort, though the latter furnish by far the most--an estimated 75 to 90
percent. The overall magnitude of the problem is indicated by the fact
that the more than 60,000 square miles of the Appalachian region
underlain by coal, including the Potomac fraction, contributes five to
ten million tons of sulphuric acid annually to streams and rivers, a
rate of production that is expected to continue for at least a thousand
years.

At Westernport the North Branch enters more populated realms, and
receives one of its latter big doses of acid from Georges Creek, which
drains a devastated, economically depressed valley mined since very
early days. This creek may be the single most unfortunate stream in the
Potomac Basin, for the accumulation of raw wastes it brings down from
the valley's communities is pickled rather than assimilated by its
heavily acid water.

[Illustration]

In the 40 or 50 miles below that point, the North Branch accumulates
great quantities of more usual kinds of pollution as it runs down a
broadening valley past towns and industries that have grown up because
of the conjunction of coal, timber, water, and railways--and in the old
days water transport, for flatboats used to shoot the river at high
water, and later the C. & O. Canal operated upriver as far as
Cumberland. Treatment of wastes in this reach is spotty and mainly
inadequate. Some industries and towns sluice them raw into the dark, sad
water, and others give only perfunctory primary treatment; the city of
Cumberland releases the equivalent of about 18,000 persons' body wastes
each day as effluent, besides extr