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or to ignore it, during prolonged use salt water penetration from downstream would take place as fresh water was withdrawn above and not replaced.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.
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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 a.s.signed 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 quant.i.ties 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 ma.s.sive 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 a.s.sert 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 quant.i.ties of stored water needed for the Basin"s near future are relatively modest in comparison to potential supplies, and a mult.i.tude 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 munic.i.p.al 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 sh.o.r.es.
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. Ca.n.a.l, 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 sh.o.r.eline, 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 ma.s.s encroachment with which it is imminently threatened, and be utilized princ.i.p.ally as part of a major park complex protecting the river and its sh.o.r.es. 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 princ.i.p.al 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 ma.s.sive 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.
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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.
Flooding in the Basin
The subject of floods is fraught with more drama than that of water shortages, for a flood can be not only a hardship but a catastrophe. For this reason, accounts of floods tend sometimes toward exaggeration, and appeals and proposals for protection against flood threats often take on the highpitched tones of impending disaster. The subject badly needs sober public understanding, despite the fact that for decades a good many knowledgeable scientists and engineers and planners have been laying out their conclusions for general perusal.
Rivers are supposed to run out of their banks occasionally.
Topographically, stream flood plains--the expanses of flat bottomland that have been deposited over long periods of geological time by the streams they border--are similar to what legal terminology calls "attractive nuisances." Men have always known that they were dangerous and yet have always utilized them to some degree, because they contain the best farm land, are convenient to water, and are easier places in which to build houses and factories and roads than are the safer hills and uplands.
In times before engineering technology was able to erect such effective control structures as today, populations who had lived along "flashy"
watercourses long enough to learn their habits tended to build their more valuable structures back away from the parts of the flood plain that got wet most often, leaving those parts for cropland and timber, or sometimes for shacktown, promenades, and parks. Thus long-settled countries and regions have often developed through trial and error a degree of what is now called "pa.s.sive flood protection," which simply means recognizing that the flood plain is sometimes a rather perilous place, and treating it accordingly. It was valid in past ages, and it is still valid today.
The Potomac Basin has been inhabited by civilized men since long before modern engineering evolved. Possibly early town-builders" wariness of floods contributed to the fact that the problem of flood damages here, though quite real, is somewhat less severe than in certain other sections of the nation. At specific points of concentrated flood plain development--Petersburg, W. Va., on the South Branch; c.u.mberland, Md., and the areas upstream from it on the North Branch; and metropolitan Washington at the head of the estuary--figures show significant amounts of average annual destruction by rampaging stream waters. In headwater areas or small urban watersheds scattered throughout the Basin, there are a number of other places where some damage takes place, whether agricultural or structural. The total average annual damages for the Basin, as computed in the 1963 Army _Report_, amount to about $8.6 million.
Along small streams, whether urban or rural, the same principles apply as along large ones, and the proper protective measures are similar if smaller in scale. Leaving the worst parts of the flood plain in fields or parks is the usual and effective form of pa.s.sive protection. Where existing development demands structural measures, it has been common practice to cover streams over as sewers or to confine them to straightened concrete channels that sluice rainwater and mud away as fast as they will flow--though often this is not fast enough, as is shown by occasional messy and costly overflows of Four Mile Run between Arlington and Alexandria. And the loss of pleasant brooks and creeks through such practices is a heavy price to pay.
More and more often lately in such cases, a combination of some pa.s.sive protection with the small headwater dams that "catch the water where it falls" and soil conservation measures to protect the watershed lands above the reservoirs, has proved to be a better solution. This is what has been done in the Rock Creek watershed in the District of Columbia and Montgomery County, Md., and its value was shown during the heavy rains of September 1966. Here stream valley parks have given pa.s.sive protection for a long tune, though the popularity and heavy use of the parks have caused a big investment in picnic areas, playgrounds, and other facilities, which themselves have often suffered expensive flood damages. As a result of long effort by a watershed a.s.sociation, two S.
C. S. dams had been finished shortly before the September flood at the only useful sites on the creek"s upper branches that rapidly spreading residential development had left available. They kept runoff from the big sudden rains entirely in hand in Maryland and reduced damage in the Federal park in the District to a point far below what it would have been without them.
Ideally, of course, such planning should be done before heavy development, and a pilot urban watershed program of this sort is being undertaken in the Pohick Creek basin on the metropolitan fringe in Fairfax County, Virginia. With freedom to locate necessary structures in the right places and to protect them against silt and ruinous runoff by requiring good land treatment and a sensible distribution of buildings, pavements, and wooded or gra.s.sy open s.p.a.ce, planners there ought to get good flood protection while preserving a pretty valley and stream for the people who will be living in the neighborhood. From any number of standpoints, this is vastly preferable to the more usual traditional procedure of letting growth run wild and then trying to cope with trouble when it comes up.
The headwater dams are equally effective in reducing flood damages in small rural watersheds where losses warrant their installation. But even on a ma.s.sive scale of installation they have little influence on downstream flooding along the main rivers. In such places--at c.u.mberland, Petersburg, and the Washington metropolis, and at certain other river towns where less damage occurs--other measures are going to have to be selected and applied in each individual case according to costs and benefits, physical possibilities, and the best interests of the region.
c.u.mberland and the lesser damage centers on the North Branch are scheduled for the cla.s.sic engineering solution of big dams upstream. The existing Savage River reservoir, finished in 1950, has cut down flooding notably in that area, and a dam at Bloomington above Westernport, already authorized by Congress, will relieve it still more, as well as fitting into the complex clean-up task along the North Branch and furnishing water for local and Washington use.
The 1963 plan proposed similar protection for metropolitan Washington and for Petersburg, West Virginia, in the form of major reservoirs at Seneca and Royal Glen. Physically and culturally, there is very little similarity between the two communities, but their flood situations and the potential effects of the proposed protective structures have a certain kinship.
At both places there has been development of the flood plain, with the result that damages occur when the communities" respective rivers get out of their banks. In relation to its size--around 2000 people--Petersburg is subject to much heavier trouble of this sort than the metropolis. It sits near the head of the lovely narrow farming valley through which the main downstream South Branch flows, a few miles below the point where two princ.i.p.al forks of the river join after rushing out of the mountains. In June of 1949, a flood there claimed five lives around Petersburg and three at Moorefield downriver, where still another main fork comes in, and wrought major destruction through the neighborhood.
The 1963 Army _Report_ calculated Petersburg"s average annual flood damages at over $200,000, and advocated construction of a $30 million, multipurpose reservoir at Royal Glen just upstream from Petersburg, to do away with most of the damage and to permit further industrial development of the flood plain, as well as to provide a great deal of water for downstream use and for regional recreation. People and groups in the area with interests standing to benefit from the reservoir were naturally in favor of it. Under present Federal policy--which will be mentioned again--its flood-protective function would cost them nothing, whereas levees or other locally effective approaches would demand a good deal of local effort and outlay, besides disrupting the town"s aspect and its relationship to the river.