contiguous zone waters provide almost universal objective evaluation standards. Armed with those legal definitions, it is possible to speak with considerable confidence on the current prevalence of water pollution. The Federal Water Quality Administration * attempted in the summer of 1970, for the first time in the history of the nation, to make just such an assessment for all waters of the nation. Field offices in the nine FWQA Regions estimated the percentage of the stream miles in each of the 233 second order watersheds in the contiguous United States (in addition to Alaska, Hawaii, Puerto Rico, Guam, the Virgin Islands, and American Samoa) that could be said to be polluted. Pollution was defined very strictly as a demonstrable and recurrent breach of any of the physical or chemical criteria applying to waterbodies, and not merely as violation of regulatory requirements imposed upon waste dischargers. In addition, for each watershed the assessors estimated the relative weight of eight general classes of activity in causing pollution. Water pollution may take so many forms that experience and judgement are essential in making determinations. A few years ago, for example, few even considered the possibility that mercury might be a significant pollutant: the element is so scarce and so expensive that its wasting was considered to be highly improbable. There was, then, no known pollution of water by mercury so long as nobody looked for mercury. And any of the natural elements in any of their inconceivably large number of compounds-including living onesmay pollute when present in excessive concentrations. The task of identification is an enormous one, and it is possible that the assessment fails to include the effects of obscure or unexpected pollutants. Given these difficulties, it is impossible at this time to produce any objective comparative index of pollution which takes account of the multi-dimensional factors which cause pollution. At this point, assessment can be made with fair assurance with respect to one dimension of a [p. 46] multidimensional problem. It can be said that water pollution from a specific pollutant does or does not exist for specific places in waterbodies at a given point in time. But there is no universal procedure for relating to the statement of prevalence either time or intensity in a completely general way. It can for example, be said that a river is more polluted or less polluted than it was five years. ago if the concern is with adverse effects of the same pollutant. Now the Water Quality Office, Environmental Protection Agency under provisions of Reorganization Plan No. 3, 12-2-70. Similarly, comparisons may be made between Stream A and Stream B if the measure of concern is common. But the quantitative measure of the change in the state of pollution if the types of polluting substances are varying is undefined. How, after all, does one weigh a one part per million improvement in the dissolved oxygen concentration of the Delaware River in August against a fifty percent increase in annual production of blue-green algae in Lake Erie? Can one possibly set a five part per million reduction in the fluoride level of Idaho's Portneuf River against a two degree average temperature increase in Maryland's Anacostia River and say that the aggregate water quality of the nation is better or worse? Another point deserves to be made about the water quality assessment that is summarized here. It is obviously impossible to provide sufficient data over a sufficient period of time to define in precise, quantitative terms what the quality of the nation's waters may be at any time. Rich as the U.S. is, its economy does not have the resources to conduct such an undertaking. What exist are samples of water quality made at different points and different times. In many cases fixed location testing stations provide recurrent data. In other cases, particular water quality monitoring campaigns have produced background data at a single point, or series of points, on a single occasion or at intervals. On the basis of such data, knowledge of streamflow, and other influences on quality, the assessors have extra-polated judgements. They are, like most scientific generalities, quasi-objective status reports and not actual measurements. The assessors, then, are critical elements of the assessment. The evaluations considered were prepared by men who are, by training and by inclination, attuned to the probability of pollution. The jobs they perform, the experiences they have accumulated, their status, the whole complex of conditions that has given them a particular view of the world, incline them to pessimism. If they err, it is likely to be in the direction of overstatement. These reservations are expressed not to cast doubts on the assessment-it is, after all, a compendium of the judgements of the best qualified professionals—but to indicate the volatile nature of the pollution phenomenon and to provide possible explanations of what may seem to be anomolies. [p. 47] A REGIONAL BASE FOR COMPARISONS The assessment of the prevalence of pollution prepared by Regional Offices finds that almost a third of U.S. stream miles are characteristically polluted. (CF Figure 2.) Half or more of the total stream miles of over 20% of all second order drainage systems* in the U.S. have been assessed to be polluted. In almost 50% of our watersheds, 20% to 50% of total stream miles are considered to be polluted. Less than 10% of U.S. second order drainage systems were characterized by the assessors to be unpolluted or moderately polluted. There are distinct regional differences in the prevalence and ostensible causes of pollution. The most general statement of the distinction is that States lying west of the Mississippi River appear to have relatively more miles of polluted stream than do States that lie east of the Mississippi. The fact is entirely consistent with our understanding of the causes of water pollution, the effects of which are magnified by low natural streamflows. Much of the Western United States is arid, and that underlying deficiency in the quantity of water makes the task of insuring adequate quality more difficult than in the humid East. But the distinction between East and West does not adequately characterize the variety of the American water pollution condition. Comparative analysis requires somewhat finer distinctions. For analytical purposes, then, a set of regional groupings are proposed here to distinguish groups of States characterized by similar climatic and hydrologic circumstances, and also by obvious consistencies in economic specialization, demographic trends, and water pollution control strategies. Six broad groups are proposed, three lying east of the Mississippi River, three west of the Mississippi, (See Figure 3.) The Pacific Coast States (Washington, Idaho, Oregon, California, and Nevada) combine moderate, humid climates in a thin, densely populated coastal corridor with an arid, sparsely settled eastern plateau that occupies most of the land area. Population growth exceeds that of the other five broad regions; and a distinctly larger portion of the area's population is concentrated in standard metropolitan statistical areas than in the other regions. A very high percentage of the * The nation's river systems are geographically classified for purposes of hydrologic description. There are major basins which encompass the waters of the coterminous U.S. These are further subdivided into 233 sub-basins. It is to these that the term "second order" drainage systems apply. They are shown in Figure 4. [p. 48] |