What is a water quality index (WQI)?

A water quality index (WQI) is designed to simplify complex water quality data by consolidating various water quality parameters into a single numerical score. This score provides an accessible and understandable representation of the overall health of a water body, making it easier for stakeholders, such as policymakers, researchers, and the public, to assess and compare water quality conditions over time or among different locations.

In creating a WQI, multiple parameters—such as temperature, pH, dissolved oxygen, turbidity, and nutrient concentrations—are typically evaluated and weighted based on their relative importance to human health and environmental quality. By reducing these diverse measurements to a single score, the WQI helps to communicate the state of water quality in a consistent and standardized manner, facilitating decision-making and prioritization of management actions.

Other options refer to broader or different aspects of water quality assessments. A comprehensive report on river health encompasses a detailed analysis of multiple factors regarding river ecology, hydrology, and socio-economic influences, rather than focusing solely on summarizing the data into a score. While determining pollution levels is important, it is just one aspect of water quality and does not encapsulate the broader purpose of a WQI. Lastly, legal requirements for water testing pertain to regulatory frameworks and do