Preventing and controlling pollution of water resources, both surface and underground, has come to be firmly established as a function of government in view of the far-reaching economic, social and public health implications of widespread degradation in the quality of available water resources. In principle and in administrative practice, preventing and controlling water pollution is distinct from controlling the quality of water supplied by public utility concerns to the general public for human consumption and other associated uses. The quality - or purity - of this water, also styled "mains water", after it has entered the supplier's mains is subject to standard prescriptions laid down in response to the paramount concern for the health of the public which consumes such water for drinking, cooking, washing, and bathing. These prescriptions bear no relationship to the more general rules which seek to avoid a deterioration in the quality of water in its natural state, before it is tapped for conveyancing to the general public. Furthermore, ensuring the purity of mains water is a function of the public utility responsible for the water supply service, and it responds to a paramount non-negotiable public health concern; preventing and controlling pollution of raw water resources, to whatever use they be put - be it domestic or industrial or irrigation or stockwatering or recreational or just preservation of the waters in their natural state - is instead a function of general government, dictated by a host of mostly negotiable factors at play in the political and in the legislative drafting and law implementation and enforcement processes. At the same time, the quality of "raw" water and that of "mains water" interface at the level of measures for the prevention and control of pollution of raw water intended for a public water supply. There is little doubt in fact that the more uncontaminated the source of water supplied to the public, the purer will be the water at the tap - or, at least, the lesser the treatment required at the water supply system intakes. Given the limited scope of this book, however, this chapter will focus on preventing and controlling water pollution in general, without regard to ensuring the wholesomeness of mains water.
Pollution of water resources is known to originate from a variety of sources. These can be conveniently grouped into two basic categories styled, respectively, "point" and "non-point" or "diffuse" sources. The former group is identified with pollution traceable to specific sources, such as industrial outfalls, domestic drains, municipal sewers and wastewater treatment plants, injection wells, and waste dumps, whose entry point into specific bodies of water, surface or underground, can be determined with sufficient accuracy. "Point" sources may impact the quality of water also indirectly, via deposition or dispersion on the ground or just leakage. "Point" sources may thus have a "diffuse" effect on water quality via overland runoff or percolation under the ground which may be difficult or impossible to trace with accuracy to the ultimate origin. The "non-point" category groups sources whose discrete origins are difficult to pin down with accuracy, such as the runoff of agricultural land where fertilizers and pesticides are employed, or the runoff of urban stormwater, and whose point of entry into water bodies - surface or underground - is difficult or impossible to determine with accuracy. In view of the comparatively recent vintage of principal legislation enacted to tackle this latter group of sources, far fewer - but no less significant - examples of subordinate legislation have been uncovered for presentation in this book.
The alternative to the government assuming it amongst its functions is for the control of water pollution to be left at the hands of the general public and, in particular, to the initiative of citizens who have a cause for complaint which is actionable before the courts. The complexity, uncertainty, length and costs of court battles initiated to vindicate the specific property rights of individual complainants or "diffuse" non-property interests of groups or classes of complainants have resulted in a shift to direct government intervention in a vast majority of countries, and a parallel shift in emphasis from remedying the effects of pollution to preventing this from occurring. In response to this generalized trend, and also in view of the far greater specificity which characterizes legislation regulating this particular function of government as opposed to the general procedural rules governing action in the courts, this chapter will focus on the former only and on the relevant operational mechanisms in particular.
A policy decision to replace government-directed pollution prevention and control for litigation-driven court action to remedy the effects of pollution is typically implemented through the adoption of legislation subscribing to one or any combination of a variety of approaches to achieving water pollution control goals. These approaches tend to fall into one of the following basic categories, namely, (a) forbidding the discharging of wastes into bodies of freshwater, on the ground or under the ground; (b) restricting such discharges through permits, licences, consents or authorizations granted by the government - the mentioned terms can, for practical purposes, be taken to be synonymous, and will be collectively referred to as "permits" in this Chapter; and (c) charging for the discharging of wastes in such a way that the external costs of pollution are factored or "internalized" in the discharger's decisions. These approaches are employed primarily in connection with the control of "point-source" pollution. Another approach consists of (d) zoning and attendant land use controls. These tend to feature in legislation primarily in connection with the control of water pollution from "diffuse" sources. In addition, "diffuse" pollution from "point" sources tends to be approached in a preventative manner by (e) prescribing precautionary measures in respect of selected land-based activities.
These approaches can also be combined, and licensing of waste discharges be complemented by charges for the wastes discharged, and by absolute prohibitions enjoining a core of impermissible actions. Also, zoning is generally complemented by relative or absolute prohibitions. It should be noted that governmental control over the discharging of wastewater - also termed "effluent" - resulting from a given water utilization or process can be achieved by inserting specific clauses as to the so-called "return flows" in the permit for the abstraction and use of water reviewed in Chapter I. It should also be mentioned that the target of permit requirements - and hence the mode of achieving governmental control of water pollution via the permit approach - varies from the generic act of discharging to the construction of works instrumental to the act of discharging, and from the carrying on of activities or processes which may result in the act of discharging to the departing from standard legislative prescriptions as to the quality which the waste must meet before being discharged.
These water pollution control mechanisms generally operate in combination with other mechanisms also specifically designed to fight pollution of water, namely, standards of quality for the waste-receiving waters - also termed "ambient" water quality standards -, and standards of quality for the waste or effluent discharged - also termed "effluent" quality standards. Other specific mechanisms include inventories of the type, extent and sources of pollution, water quality management planning, and sampling and testing the quality of waters and wastes. These mechanisms complement, and are complemented by, permit requirements.
The basic policy decisions underlying the choice of approach is generally reflected in an Act of Legislature specifically dealing with water pollution prevention and control alone, or in combination with the control and prevention of pollution of other environmental media, or in conjunction with other aspects of water resources management - notably, allocation of water to different uses. In addition to spelling out the operational details of the approach opted for by the Legislature, subsidiary legislation provides for the complementary mechanisms needed to fully operationalize the course of action charted by principal legislation.