Developing a Standardized Water Quality Index for Evaluating Surface Water Quality¹

Abstract

There is a significant need for a science‐based approach to interpret water‐monitoring data and to facilitate the rapid transfer of information to water resource managers and the general public. The water quality Index (WQI) is defined as a single numeric score that describes the surface water quality condition at a particular time and location. The objective of this paper is to describe the WQI concept and the approach for developing an ecoregion‐specific standardized WQI that meets the needs described above. The premise of the proposed WQI is based on categorizing scientifically documented aquatic life responses to changes in instream water chemistry. The method uses an aggregated procedure that matches the entire range of standardized probable biological responses to standardized narrative water quality evaluation categories and standardized rank score categories. The calculation of WQI and decision‐making process are performed within an Excel spreadsheet software program. The article includes examples of the proposed WQI applications that could enhance effective water resource management and facilitate timely communication of water quality conditions to water resource managers and the general public.

Evaluating water quality of Awash River using water quality index

“…Some of them being used worldwide are: National Sanitation Foundation (NSF) WQI (Kaurish and Younos, 2007), Canadian Council of Ministers of the Environment (CCME) WQI (Worako, 2015), Overall Water Quality Index (OWQI) and Oregon WQI (Tyagi et al, 2013;CCME, 2001b;Poonam et al, 2015). Though NSF WQI (Wills and Irvine, 1996;Tyagi et al, 2013;Poonam et al, 2015), CCME WQI and OWQI (Singh et al, 2015) are indices frequently used for water quality assessment, CCME WQI is the most efficient and flexible with respect to the type and number of water quality variables to be tested, the period of application, and the type of water body.…”

Assessment of water quality of a river using an indexing approach during the low‐flow season

“…As a synthetic indicator, WQI provides overall summaries of water quality and potential trends on a simple and scientific basis (Kaurish and Younos, 2007). The concept of indices to represent gradations in water quality was first proposed by Horton (1965).…”

“…The need for such readily understood evaluation tool was ultimately realized, and several researchers (e.g. Brown et al, 1970;Prati et al, 1971;Walski and Parker, 1974;Landwehr, 1979;Bhargava, 1985;Dinius, 1987;Smith, 1990;Swamee and Tyagi, 2000;Kaurish and Younos, 2007) have developed their own rating schemes. A remarkable contribution in WQI development is a model proposed by the Canadian Council of Ministers of the Environment (CCME).…”

Mapping spatial distribution of pollutants in groundwater of a tropical area of India using remote sensing and GIS

“…The primary purpose of CA is to classify the objects of the system into categories or clusters based on their similarities/dissimilarities (Kaufman et al 1990;Scott and Knott 1974;Srivastava et al 2011). The joining or tree clustering method uses the dissimilarities (similarities) or distances between objects when forming the clusters.…”