Except for acid mine drainage, most of the Basin's main problems are
found at metropolitan Washington. Because they are primarily people
problems and more people live there than anywhere else, the problems
tend to be bigger, including that of water supply. A conceivable
shortage of several tens of millions of gallons of water per day within
the near future is not a small shortage, and small measures are not
going to cope with it.
A number of possible measures have been considered and weighed. Some
seem undesirable for one reason or another, even in terms of the distant
future. Others are unusable now, but have promise for later, when more
is known, or technological processes involved have been perfected, or
cost have been brought within reason. Still others, undoubtedly, cannot
even yet be discerned. And some will work now at prices that can be
paid. Ultimately, it seems certain, the super-Metropolis of the future
will depend on a mix of sources for its water, getting part of it by one
means and part of it by another and so on, as technology makes new means
possible, and as economy, safety, and other factors may dictate.
Therefore, there is no single "right" answer for the long run, and an
attempt to prescribe one inflexibly would compound confusion over the
years and undoubtedly perpetrate an injustice on future citizens in ways
already mentioned. We need to do them the favor of believing that they
will be able to cope with their own immediate problems at least as well
as we can do it for them, and probably in ways better suited to their
tastes.
Nevertheless, it is imperative that the city be given a margin of
drought insurance for two decades or more, and for this margin some
source definitely feasible in present terms must be identified and
guaranteed.
Going outside the Basin for any significant part of the metropolitan
water supply does not appear to be justified. Some water is presently
being drawn from impoundments on the Patuxent just north of the city,
but no more of it can be counted on. Diversion from the voluminous
Susquehanna much farther north is feasible from an engineering
standpoint. But the cost of it would be relatively high, and there are
also certain strong objections in principle, based on the facts that the
Potomac does have plenty of water and there is no inherent moral
advantage in transferring the question of development elsewhere, that
the Susquehanna Basin may well need its own water at some future time,
and that the ecological effects of such diversion on the immensely
valuable fisheries of Chesapeake Bay, which are dependent in large part
on a shifting balance of salinities maintained by the tributary rivers,
are unclear.
"Planned scarcity" of water in a community, wherein administrators and
public alike accept the certainty that during dry times lawns and parks
and golf courses and sometimes human skins will have to do without the
application of water for a spell, is a reality of life in some arid
regions and is probably always going to be. Elsewhere it is, or should
be, an element in the design planning of industries that use heavy
quantities of water for cooling and such processes. All water supply
planning must consider it, for to build against any conceivable shortage
would be prohibitively expensive. Pricing of water so as to cut down on
waste without curtailing ample legitimate use may well be a longrun
tool, as has been suggested. But in terms of general municipal and
industrial water, any great degree of calculated shortage hardly seems
appropriate for a humid-zone city which has a fine river at its doorstep
and happens also to be the national capital, so that a scarcity would be
of national concern in a number of ways. Federally established and
maintained parks and open spaces, for instance, with their carefully
tended vegetation, would be one of the first things to suffer.
Desalting of sea water, another reality now in arid zones and one of
immense importance, has a certain degree of planned scarcity built into
it by way of its price, at least at present. Some people believe that in
time this process will be refined to the point that it can furnish
abundant cheap water to all the world's seacoast cities. Certainly as it
develops it may well have a potential for marginal drought-proofing at
Washington, an emergency source to be drawn upon if needed. But the day
seems distant when it will be truly competitive in price with riverine
sources in regions of adequate rainfall.
Inland arid regions and perhaps other places as well are undoubtedly
going to find one answer to water shortages in the recirculation of
their treated waste waters through municipal systems. In one form or
another such recirculation is already working at certain places in the
United States on an emergency basis, and its full potential for
industrial use has yet to be explored. However, the indications are that
towns' and cities' reliance on it during anything but temporary
emergency conditions is going to depend on expensive methods of
refinement and "fail-safe" overdesign, plus dilution with new water,
which means again that it will probably not be competitive in price with
natural water where enough good natural water can be had. To this may be
added the observation that the consuming public presently has a few
definite lingering qualms about the idea involved, particularly if there
is other water around.
The underground rocks and sands of the Basin hold huge reserves of water
with a fundamental relationship to the whole river system, whose basic
dependable sources lie in these aquifers' outflow to the surface. Around
the metropolis, some ground water is being taken from wells even now to
supplement the overall supply and to satisfy the whole demand of any
number of outlying communities. Though locally available quantities are
limited and pumping costs rather high, such wells will undoubtedly be
highly useful for future extensions of the metropolis, especially into
the Coastal Plain.
There is also much promise in studies of the Basin's aquifers being
carried out by the U.S. Geological Survey to determine detailed patterns
of their contribution of water to the stream system and to see if it can
be regulated and made even more useful. Such a possibility has great
implications in terms of augmenting river flows both for water quality
control and water supply, and could mean much at Washington. So could
certain techniques of deliberate drawdown of aquifers to induce recharge
with excess surface waters or sometimes treated sewage effluent, also
presently under study. Ground water as a source has some unique
advantages--among them a minimum of evaporation loss, less need for
surface structures, and protection against catastrophic
contamination--and it deserves full exploration, though it cannot at
present be counted on as a significant part of the answer for the
metropolis.
Far out, though possibly not very far off in time, is the likelihood
that future water planners will be able to count on some degree of
control over a given region's rainfall and snow. Through
experimentation, this subject is rapidly being excised from the mists of
superstition that once surrounded it, and the Department of the Interior
has an active program of research and study in the West, with tremendous
implications. But, yet again, present planning cannot take it into
account except in the sense that, along with some of the other
technologies already mentioned and undoubtedly others that have not yet
even emerged to view, it adds to the near certainty that future planners
are going to have a much wider range of alternative methods at their
disposal, to choose from and mix as may seem best. And this, in turn,
reemphasizes the wisdom of flexibility in present planning and the need
to keep big irreversible decisions to a minimum.
The upper Potomac estuary from Little Falls down to the vicinity of
Marshall Hall and Mount Vernon or below contains a great deal of fresh
water, an accumulation made up of inflows from the river above the Fall
Line, local storm runoff and tributary flows, and treated sewage
returned to the tidal river. The volume of this water that would be
available for use without salinity has been variously estimated. At low
tide, there would be 9 billion gallons of fresh water in the upper
estuary from Chain Bridge to the mouth of the Anacostia River; In the 10
mile stretch from Chain Bridge to the District of Columbia's Blue Plains
treatment plant, 15 billion gallons; and, from Chain Bridge to the
saltwater front near Indian Head, Maryland, 100 billion gallons. Most of
the time now it is afflicted with heavy pollution, as will be detailed
in the next chapter of this report. But it does constitute a large
natural reservoir of potentially usable municipal and industrial water,
whose attractiveness for these purposes, as well as for all others, will
grow steadily as the pollution is brought under better and better
control. These facts have led some opponents of any and all major
reservoirs in the Basin to conclude that the water in the upper estuary
is a presently satisfactory reserve with which to face any foreseeable
metropolitan shortage of supply from the upper Potomac.
The assumption has strong appeal, but it appears to be too risky to
serve as a basis for adequate present planning to meet looming demands.
That even now the water in the estuary's uppermost reaches, above the
main metropolitan treatment-plant outfalls, would be usable for short
emergencies by the installation of relatively simple pumping equipment
below the falls, cannot be doubted. That in the long run the major part
of the freshwater tidal river at and below Washington is likely to be a
valuable source of metropolitan water, maybe a principal source, is
quite possible. Its use is and will be a strong consideration in
longterm planning--another good reason, in fact, for flexibility. But
the truth is that right now enough doubt and ignorance exist in regard
to its exact potentiality that it should not be counted on to provide a
safe margin of supply under all conceivable conditions during the next
twenty years or so, for which planning provisions need to be more rigid
and definite.
The doubts and unknown factors have to do mainly with the quality of
this water, which comes under discussion later. In abridged summary of
relevant facts at this point, it may be observed that unless all sewage
and sewage effluents were collected and diverted to points well beyond
the limits of the upper estuary, use of its water for periods beyond a
few days of emergency would become essentially a form of recirculation
of waste waters--with, at this time, the main drawbacks that we noted in
regard to that process and certain others besides. For, under the
low-flow conditions that would bring about its use, the effluents in the
river below the mouth of the Anacostia would penetrate upstream as water
was pulled out below the falls and would reach the pumps in fairly short
order, probably moving in a tongue up the main channel.
With the radical improvement in the functioning of the metropolitan
treatment plants that must be achieved, and other measures to relieve
pollution in this part of the river, valid objections to such
recirculation will of course weaken and ultimately disappear. But no
one can reasonably expect that these things are not going to take a
certain amount of time--quite conceivably enough time to run the city up
against an emergency it could not handle without other, more standard
sources of auxiliary water. Besides the matter of consolidating and
improving treatment of collectible wastes, there are certain other
diffuse and stubborn sources of pollution, as will be seen, for which
good counter measures simply do not yet exist--among them are surface
runoff during local storms and overflow from combined sewer systems.
If the collectible wastes were diverted out of the upper estuary and if
it proved possible to cope quickly with other pollution or to ignore it,
during prolonged use salt water penetration from downstream would take
place as fresh water was withdrawn above and not replaced. Studies on a
mathematical model of the estuary indicate that under conditions that
could materialize, this would make the water at the intake too salty for
use. A barrier dam across the entire estuary at one or another point in
the freshwater section could prevent such penetration, but would be
hugely expensive and undoubtedly more obtrusive on a much-used part of
the riverscape than most upstream reservoirs could possibly be.
Furthermore, even if all these doubts and areas of ignorance were to be
easily resolved, insistence that the upper estuary is the only logical
answer to metropolitan Washington's water problem ignores the fact that
major water demands are building fast in certain already-mentioned areas
of the upper Basin, and that, since the Basin is a hydrological unit,
measures to satisfy these demands can easily, economically, and quite
logically be designed to furnish a good part of the metropolis'
near-future safe margin of water supply as well.
[Illustration]
A need for vigorous research specifically directed toward exploring all
these alternative means of supply is evident. If it moves fast enough
and the knowledge that comes out of it is made available to planners, it
may very quickly make a great difference in the kinds of sources of
water they can turn to for the solution of problems, just as studies
since the early 1960's, when the Army work on the Potomac was completed,
have altered prevalent ideas about pollution control through flow
augmentation, and have therefore greatly diminished the overall amount
of water considered necessary to meet the Basin's demands.
In the crucial meantime, the established certainty of storage in
reservoirs is available. In river basins with reasonable annual amounts
of precipitation but with human demands on streams that sometimes exceed
the rate at which water flows down, such reservoirs are still usually
the most dependable and efficient item in the present technology of
water supply. And since they generally have other purposes to which
proportionate shares of construction costs are assigned in individual
cases--flood protection, water quality control, navigation,
hydroelectric power, recreation, silt detention, etcetera--they tend
often to be the most economic sources of big quantities of water. In one
form or another they have been built from very ancient times, and they
have been indispensable to the useful development of water resources in
our expansive economy.
In parts of the United States far from sea-coasts or large natural
lakes, reservoirs built for water supply and other purposes have become
the focus of enormously popular forms of recreation that would otherwise
be impossible in those regions--sailing and motorboating and
water-skiing and the sort of fishing possible only on big water, and
such things. Properly designed and located, they can be beautiful bodies
of water, as the vacation homes that grow up around many of them
testify.
Strong objections to them also frequently are voiced. They are one of
the most massive manifestations of man's technological ability to adapt
natural processes to his use, and they sometimes have profound effects
on fish and wildlife and the whole ecology of a stream system region, to
the dismay of many conservationists. Often too they flood out large
areas of riverbottom farmland and other private property, arousing the
ire of some rural folk and small townsmen who feel that their interests
have been sacrificed to the water or flood-protection demands of
downstream city dwellers. Opponents of major dams sometimes assert that
many of them have been built not to meet real hydrological needs but to
foster economic development which may or may not materialize and may or
may not be worth the loss of natural or scenic or agricultural resources
disrupted by the reservoirs. Other thinkers, not necessarily against
reservoirs in general, express a doubt that the potential effects of
specific structures are always thought out sufficiently beforehand.
Among these are the authors of a recent publication of the National
Academy of Sciences--National Research Council, _Alternatives in Water
Management_:
"_We create great reservoirs that stop the migration of fish and then
provide costly fishways, hatcheries, and other devices to maintain the
fishery, and with no certainty of success. We impound water without
knowing the effects of that impoundment on its quality. We build an
irrigation project and then find salinity increasing dangerously in the
river downstream. We eliminate high-flood peaks by reservoir storage,
but downstream from some reservoirs we see unpredicted erosion,
sedimentation, bank-cutting, and other effects, even unto, as in
California, the loss of beaches along the seacoast, starved of their
supply of sand._"
The list of objections could be extended--and often is by objectors--to
a point of pettiness. Nevertheless, the main doubts are gaining much
acceptance and are imperatively having to be taken into account more and
more these days, as new elements of water technology and
philosophy--some of them mentioned earlier in this chapter, others to
emerge in subsequent discussions--come closer to full feasibility and
become a part of general human knowledge. Delay in building reservoirs
until it is certain they are needed is on the verge of becoming a
respectable element in planning, and in the future dams may well become
merely one of many ways to guarantee water and handle it. At least some
water authorities, though certainly not all, have voiced the opinion
that most present reservoirs will some day serve primarily for
recreation, if emerging new principles of water supply, water quality
improvement, flood protection, power generation, and such things attain
general use.
That day, however, has not yet dawned, nor is the interim before its
arrival calculable. It is necessary to face present reality with present
tools, and the reality at the Washington metropolis and elsewhere in the
Basin is that a good deal of water is going to be needed rather soon,
and that no reasonably economic alternatives with any clear esthetic and
ecological advantage over reservoirs are presently available to furnish
it.
Nor, if planners and designers are aware of the whole set of problems,
do reservoirs necessarily have to be weighty in their impact on the
natural scene and the public interest. The quantities of stored water
needed for the Basin's near future are relatively modest in comparison
to potential supplies, and a multitude of good reservoir sites exist to
be chosen from. There is no reason why, with present knowledge, a
minimum of necessary reservoirs cannot be planned and designed for a
maximum of beauty and pleasure. It is a notable fact that a very large
number of Americans prefer boating and fishing and other aquatic sports
on reservoirs to any other form of recreation, and another notable fact
that in the upper Potomac Basin there are very few places where even
small numbers of Americans can thus indulge themselves at present.
In terms of metropolitan Washington's water supply, considered apart
from other Basin water problems, the best reservoir site by far in the
whole Potomac drainage would be the old River Bend site or the one
proposed in 1963 at Seneca, both just upstream from the Falls above the
metropolis. In one package, either of them would impound enough water to
take care of any likely municipal and industrial demands of the
metropolitan region for more than a half-century, besides trapping most
silt from upstream to keep it out of the estuary, and providing a good
measure of protection for flood-susceptible metropolitan shores.
Furthermore, the proximity of such a reservoir to the city would ensure
a great deal of aquatic recreation for people there and would somewhat
simplify water management problems.
Thus, it is natural that Seneca, the latter proposal of the two, has
found strong champions among metropolitan administrators, water
engineers, and planners whose thinking has to be primarily in terms of
sure and efficient water supply and flood protection. It has found
equally strong opponents, however, enough of them to have stalled it to
date. It is not yet dead, for it emerges in each new discussion of the
city's water situation. It will not be dead until the metropolitan water
problem, short-term and long-term both, has found a full satisfactory
solution in other terms.
Our feeling remains unchanged since the publication of our _Interim
Report_: that when all factors are weighed and future uncertainties are
taken into account, Seneca should not be built at this time. If the
price in money would not be high in relation to immediate "market"
advantages gained, the permanent price, in river and countryside and
those other intangibles that are getting to have more and more weight in
men's minds year by year, would be heavy.
The full main stem Potomac, carrying the water from the combined North
and South Branches and the Shenandoah and the other upper tributaries
down through the Blue Ridge water gap and across the rolling Piedmont
and the Fall Line, is at its most typical in the 39 miles from Harpers
Ferry to Great Falls. Seneca as originally proposed would inundate 35
miles of this stretch, together with islands and bottomlands, forests of
big hardwoods, meadows and productive fields, and that much-used
segment of the publicly owned C. & O. Canal, with the trail along its
wooded towpath. Even reduced in size and designed as strictly a water
supply structure, it would have many of the same effects. There is
special and tranquil beauty in this piece of the river, which makes a
fine float trip and is much fished, as well as a lot of historical
significance dating back to the Senecas and the Piscataways and before.
Here these things are not forgotten and removed from men's reach but are
available to metropolitans who go to the trouble to seek them out, as
many do. Nor is there anything else around to take their exact or even
approximate place if they were gone.
It has been pointed out that if the metropolis grows according to
predictions, a major part of that growth is going to be upriver, and the
main stem of the Potomac will have the same relationship to the
metropolis of the future that Rock Creek has to the Washington of today.
Thus the decision that is made about the main stem in our generation is
similar to the decision that planners had to make about Rock Creek
three-quarters of a century or more ago. Those planners decided
magnificently well, bequeathing to the future an urban stream and park
unique in this country and perhaps the world, a treasure that the public
is presently defending against other, newer, subtler threats than mere
damming or encroachment.
A reservoir above Seneca clearly could not mean that sort of thing. It
would be a useful lake, but devoid of the changeless tone of the
Potomac as it flows there now. The reservoir's proper functioning would
require fluctuations in its level, with occasional ugliness at the
shoreline, and if it would permit a great deal of happy water-skiing and
flat-water fishing, the same opportunities are going to be available to
Washingtonians in the nearby estuary when it is suitably cleaned up,
even though the section immediately adjacent to the metropolis may take
a good while to bring up to swimming standards.
In terms of the overall good of the people of the metropolis and the
Basin and the country, the water situation at Washington now and during
the near future hardly bears a desperate enough aspect to warrant the
sacrifice of much of the main flowing river to a reservoir which, like
the freshwater estuary, could not be meshed with upstream needs but
would serve only the urban areas at and below the Fall Line. Conceivably
at some future time, if technology should renege on its promise to bring
forth good new alternatives, and population pressures continue to grow,
the city may badly need a reservoir there. It is a uniquely valuable
site. For that reason, we repeat our Interim proposal that the reservoir
site, minimally defined, be preserved against the mass encroachment with
which it is imminently threatened, and be utilized principally as part
of a major park complex protecting the river and its shores. To defer
irreversible decisions and to leave them as much as possible to future
generations whose conditions of life and desires we cannot predict with
accuracy, can be a principal way of maintaining freedom of choice.
In the category of reservoirs, at the other end of the spectrum are the
comparatively small headwater dams that the Soil Conservation Service
has been designing and supervising for three decades in authorized
watersheds throughout the country. These structures can serve several
functions and can furnish for small watershed areas and small centers of
population many of the benefits that the Corps of Engineers and Bureau
of Reclamation dams furnish for large areas. On their own scale, they
are vulnerable to some of the same objections that are aimed at large
reservoirs. But the scale is smaller; they tend to be less imposing and
pre-emptive of good land than big river dams, "catch the water where it
falls" to hold it for local use and to alleviate local flooding, and are
backed up by erosion control practices in a program that has proved to
be one of the best available stimulants to good land use. For these
reasons they have appeal for many rural people and conservationists.
* * * * *
However, the conclusion which some of their supporters have reached is
that if only enough of the small dams could be built throughout the
headwater areas of a river basin, they would eliminate the need for most
other forms of water management, leveling out flood and drought flows
and holding a great aggregate amount of water on tap for use anywhere
down the line. At times in the past, the controversy between supporters
of big dams and supporters of little dams achieved the proportions of a
bloodless war, but after a good many years of testing and observation
it is now generally agreed by hydrologists that both have their place
and that the most appropriate focus for the small dams' functioning is
local.
At any rate, they are not an answer for Washington's problems. Even if
enough of them were installed specifically to provide the storage volume
needed for metropolitan use, the question of operation--ensuring and
coordinating releases from a large number of places at varying long
distance upstream from the point of intended use, in such a way as to
make the required volumes of water arrive at the right time, without
waste--would be very difficult even with much more sophisticated and
expensive design than these structures customarily have. Without it the
problem would be insuperable.
* * * * *
Thus, for metropolitan Washington's water in the near reaches of the
future, some reservoir storage is indicated with fewer ecological,
recreational, and scenic drawbacks than a Potomac main stem dam, and
more efficiency for massive supply than the small headwater structures.
Since the Potomac river system is a unit, with the metropolis at the
downstream end of its non-tidal part, water stored anywhere in the upper
Basin can be released for use there. This gives much freedom of choice
in the selection of sites for reservoirs and in the combination of
releases from various places to make up an adequate total supply, though
obviously good management will be needed to coordinate the releases and
avoid the waste of water.
It also means, if good principles of river-basin management are
followed, that reservoirs to supply water at Washington can be located
and designed so as to satisfy major upstream demands at the same time,
and that they can be fitted in with regional and Basin needs for water
quality improvement, flat water recreation, and in some places flood
protection. In such conjunctive planning, based in the Basin's physical
unity, commencing now and continuing on into the future as new needs and
new ways of satisfying them come to view, lies the main hope of
developing the Potomac water resource in such a way as to avoid waste of
money, waste of water itself, and waste of the landscape and the general
environment. Without it, nothing can result but a piecemeal haggling to
bits of the river system as local demands grow acute and local pressures
force the adoption of one-shot measures. With it, towns and areas and
industries can be guided toward sensible and thrifty action that fits in
with the wellbeing of the whole Potomac region--toward buying a share in
the water of a rightly designed, rightly placed reservoir large or
small, toward development of ground water resources where these are
adequate, toward the use of new technology that may be feasible and
suitable.
[Illustration]
[Illustration]
The range of choices is certain to enlarge with time, and the ease with
which right choices can be made. In this computer age, mathematical
models of river systems, including the Potomac, are at work manipulating
hydrological data and quickly indicating optimum coordinated solutions
for given water problems that formerly would have taken many weeks to
solve, if indeed men could have arrived at such exact solutions at all.
Computers are no better than the material that is fed them, however, and
the need for new water data--for facts--is acute, if computers and the
men who run them and the policy makers to whom they report are to pick
the best ways of doing things. So is the need for means of giving
"intangible" values their right weight in the whole process. But the
computers are the keystone of the new technology and they are going to
make right coordination simpler.
With coordination also, as we shall see hereafter, there is the
strongest possibility of getting the river system clean again and
keeping it that way, and furthermore of vouchsafing some measure of
protection to the landscape through which it flows. For the physical
unity of a river basin has many implications, and not the least of them
is that the people who live there can be guaranteed at least a physical
chance to lead full and wholesome lives.
Water supply for upstream areas of the Basin, then, is not a separate
thing from water supply for the downstream metropolis and should not be
treated as separate. They are all drinking from the same fountain. Where
an upstream demand is great enough or is going to be great enough in a
short span of years to warrant major storage, that storage must be keyed
in with all other demands that it might meet or help to meet, including
that at Washington. Where an area of lesser need is shut off by its
location from sharing in such major storage, groundwater development or
headwater reservoirs may well be the answer, but these measures too
should be made to serve as many purposes as may be required for the
protection of the area's whole range of interests and the good of the
entire Basin. The need for such interweaving--for coordination, for
planning and action that are unified--is primary, and will emerge again
and again.