The lower estuary
Downriver from the main effects of the metropolitan complexities, the widening brackish and salt portions of the Potomac estuary form a generally healthy body of water, though changes loom as the metropolis moves inexorably outward from its center and as hitherto remote Tidewater areas are brought more and more under the influence of modern ways of being. Localized problems of pollution point to general dangers that will certainly materialize unless safeguards are set up in time, for estuaries are delicate, immensely productive, and still somewhat mysterious aquatic environments that have been and still are too much taken for granted.
Rapid human intrusion on estuaries during the past twenty years has been making apparent their phenomenal value in a natural condition. Vulnerable, attractive to diverse interests that work their beds for sand and gravel and fill in their marshes for development and casually pollute them, they have recently been called America's most endangered natural habitat. They are almost unbelievably fertile places, with involved biological cycles that can convert the fertility into usable food at rates per acre far exceeding those of the finest farm land; in terms of money, one recent set of experiments indicates the possibility of attaining an annual shellfish production on tended beds worth over $26,000 an acre.
Furthermore, aside from the direct harvest of this wealth from estuaries each year by commercial and sport fishermen, these in-between waters make an indispensable contribution to the entire Atlantic coastal fishery, an industry worth a billion dollars a year. The reason for this is that at least 70 percent of coastal fishes spend some essential part of their life cycle within an estuary—spawning there, or passing through on their way to spawn in running fresh streams, or moving in as fry from the rivers or the open sea to find a "nursery" in one of the varied estuarine habitats—bays, marshes, sandy shorelines, mudflats, tidal creeks, or weed beds.
The oysters from the famous beds in the Saint Mary's River off of the lower Potomac are mainly condemned as unfit for consumption because of local sewage pollution, and these beds are not the only unfit ones, for towns and resorts in the region have been growing and sanitary facilities have not been keeping pace. Already some arms of the superb natural harbors formed by the tributary creeks are noxious with discharges from boats at big marinas, and gravel dredging is stirring up silt to smother bottom life, including shellfish. As Tidewater agriculture revives and modernizes, pesticides and artificial fertilizers are coming to be as much a part of the scene there as in other farming regions, and may be expected to influence the estuary—in fact, they undoubtedly already are doing so in subtle ways with effects not yet apparent.
Yet most of this part of the river is still beautiful and continues to yield good harvests of seafood. The Potomac River Fisheries Commission has been alert to obvious dangers and has moved against them where its powers have permitted, and natives of the area are increasingly alert in protecting the estuary. Many of them depend on it for a living, most are oriented toward it for their pleasures, and until lately a good many of them counted on it for transportation. In a number of different ways, it matters in their lives. And that fact offers some hope for the future, especially if it is fostered and strengthened by overall protective measures.