Dinius’s Second Index

Increasing levels of water pollution, with resulting billion-dollar use and control programs, necessitate development of water quality indices that provide a means for quantifying and evaluating the quality of a given body of water. Because data output of current water monitoring stations is enormous, and dimensional reporting units are varied and do not combine in a straightforward algebraic manner, even scientifically trained users are unable to assimilate the data and report “true” quality of water without some methodology to provide data simplification and summation. Possibly even more serious, users with a limited technical background,such as governmental administrators and the general public, are unable to understand and properly interpret raw water quality data stated in scientific dimensional units such as micro Mohs per cm. Thus, there is a need for a readily comprehensible water quality index system that will bring the important water polluting elements together within one unifying framework. The Index of Water Quality (IWQ) would communicate the quality of water to those with limited technical knowledge just as the Air Quality Index (AQI) is widely used to communicate the quality of air to the general public. The water quality index, to be feasible and useful,must reduce the vast quantity of water quality information into its simplest form, and in the process of simplification some information must necessarily be lost. If the index iswell designed, however, the measurements used Wi-Fi be representative,and will be quantified in such a way that the pollution level reflected by these various measurements are comparable with each other and impart a connotation to the scientifically untrained, as well as to the water quality expert,of the overall quality of the water at a given time. A Planning Committee on Environmental Indices of the National Academy of Sciences Report (NAS, 1975), noting that the status of the environmental quality measurement technique was as yet unsatisfactory, focused on the following four important uses of environmental. Indices: (1) formulating government a lpolicy, (2) evaluating effectiveness of environmental protection programs, (3) designing environmental protection programs, and (4) communicating to the general public the state of the environment and the impact of government program son the environment.

Attempts to design a generalized water quality index often receive the criticism that the evaluation of water quality is dependent upon the classification of the water for a particular use. The loss of information resulting from the use of a simplifying water quality system to evaluate water quality is indeed regrettable. However, water quality has too long been without any widely applicable index because of many water quality experts’ reluctances to accept any type of simplification or aggregation in reporting water quality. It seems important that a serious attempt be made to design a system that can identify the overall water quality at various water sites. Once a generalized water quality system is set up as acontrolling framework, supplementary indexes for various water uses and special situations can be attended. In support of this position, Land wehr (1974), reporting thatO’Connor found two specific use indexes to be highly correlated with the general index proposed by Brown, et al. (1970),concludes that “one index to describe overall quality could be constructed for the purpose of communicating the status of water quality situations to the public.”

In response to the increasing concern with water quality indices, a variety of system have been proposed; comprehensive reviews of these systems have been published by Landwehr(1974) and Ott (1978a, 1978b). Landwehr (1979) reduces water quality indices to three basic types: (1) those that translate levels of polluting elements into a quality unit based on the relationship of the quantity of each element present in the water to that water’s quality; (2) those that translate levels of polluting elements into a quality unit basedon some set of standards usually established by a governing unit; and (3) those that subject the value of the variables toa variety of standard statistical procedures. The water qualityindices system proposed in this paper belongs to the first category because its purpose is to communicate “true” water quality, and standards are thus set to reflect the actual jimpairment of quality caused by the presence of each pollutant.A difficulty with systems in the second category is the useof standard levels that, because they are established by governmental units to protect human and wildlife health and welfare, include (very wisely) a wide margin for error; theydo not, therefore, generally reflect true quality of water. Indicesin the third category are usually complex and difficultto apply and are thus less suitable for a universal index.