Assessment Of Water Quality Status Of River Kibisi, Kenya Using The Ephemeroptera, Plecoptera And Trichoptera (Ept) Index

Abstract

The term water quality is applied universally to refer to the water status that meets the universal standards set for legitimate and vital water use at any scale i.e. local, regional and international levels (WHO, 2000). The evolution of the term water quality has been due to the expansion of water requirements and ability to measure and interpret water characteristics. The definition of water quality depends on the factors that determine it, and other variables that affect the nature of water resource. The introduction of harmful substances in river water (pollution) results in deterioration water quality standards (degradation), and this interferes with legitimate and vital water use at any scale i.e. local, regional and international levels (Meybeck et al., 1989). However, water quality standards have been established for regulatory purposes and are determined based on the criteria involved depending on domestic, agricultural uses and aquatic life systems (WHO, 2004). River water quality status is generally affected by many physical, chemical and biological parameters introduced by natural forces and human (anthropogenic) activities. Water quality criteria, standards and related legislation are often used as the main administrative means to manage water quality status in order to achieve user requirements. Water quality standards for surface water vary significantly due to different environmental conditions, ecosystems and intended human uses. Different uses of water raises different concerns and therefore different standards must be considered. The most common national requirements for drinking water of suitable quality for many countries are based on the standards of the World Health Organization guidelines for drinking water (WHO, 1993).