Pollution of the Potomac begins at or near its traditional source, the
tiny Appalachian spring at the head of the North Branch where in 1746
Thomas Lord Fairfax's surveyors set an inscribed stone to mark the
northwestern corner of that possessive nobleman's vast holdings.
Abandoned strip coal mines lie within sight of the spot, and it is
doubtful that the infant river trickles more than a few yards before
receiving its first injection of the acidic mixture of substances that
springs and seeps and runoff water extract from bared coal strata and
the mines' spoil heaps and carry down to the streamlet they 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 extra raw wastes whenever storm runoff
overloads its combined storm and sanitary sewer system and causes it to
overflow. Where major efforts have been made, as at the Upper Potomac
River Commission's Westernport plant below the big Luke, Maryland, pulp
and paper mill, the wastes are so voluminous and complex that some of
them still have to be dumped, and the effluent from even highly
efficient treatment further degrades the river.
Fortunately, the North Branch, acid above, deprived of oxygen and
overenriched and septic below, is not typical of the flowing parts of
the Potomac river system, but it stands as a good grim example of what
pollution can mean, and as a foretaste of what may be expected to happen
elsewhere in the Basin if it is not stopped soon. Mine acid is not a
significant problem in any streams outside of that region, but untreated
or inadequately treated wastes are badly blighting many streams and
rivers or stretches of them. Some smaller watercourses, like historic
Antietam Creek below Hagerstown, Maryland, have deteriorated under the
influence of discharges from single or limited sources, while larger
ones suffer from a cumulative waste buildup in areas of concentrated
population or industry. Some twenty miles of both industrial and
municipal pollution in the South River Branch of the Shenandoah's South
Fork below Waynesboro, Virginia, have done much damage to that legended
river for a good distance downstream, a situation that is worsening with
the area's growth. On the North Fork of the Shenandoah similar effects
have been wrought by heavy organic loads from poultry processing and
other things. The list could be extended: aside from a few happy
exceptions like the prized Cacapon, draining rugged, forested, thinly
peopled hill country, nearly all the Basin's flowing streams of any size
receive damaging loads of waste from towns and industries.
[Illustration: WATER TREATMENT STEPS
(1) River water enters here
(2) Water chlorinated
(3) Water settles. Heavy particles sink
(4) Water pumped to Pretreatment Building
(5) Various chemicals (chlorine, alum, lime, carbon) added. Chemicals
and water stirred in rapid mixing basins
(6) Slow mixing to form "floc" (see Alum below)
(7) Water settles for 2-1/2 hours. "Floc" carries impurities to bottom
(8) Water filtered through 94 rapid sand beds
(9) Final chemical treatment (chlorine, lime, fluoride, phosphate)