OREGON WATER QUALITY INDEX A TOOL FOR EVALUATING WATER QUALITY MANAGEMENT EFFECTIVENESS¹

TLDR

The Oregon Water Quality Index (OWQI) is a single number that integrates eight water quality variables and has evolved since the 1970s with improved understanding of water quality behavior. The study aims to provide a simple, concise method for expressing ambient water quality of Oregon’s streams for recreational use, such as fishing and swimming. The report outlines the historical basis and improved design of the current OWQI. The OWQI allows users to interpret overall water quality and its specific impairments, demonstrates spatial and temporal information, and improves comprehension and communication of water quality status while illustrating the effectiveness of protective practices.

Abstract

ABSTRACT: The Oregon Water Quality Index (OWQI) is a single number that expresses water quality by integrating measurements of eight water quality variables (temperature, dissolved oxygen, biochemical oxygen demand, pH, ammonia+nitrate nitrogen, total phosphorus, total solids, and fecal coliform). Its purpose is to provide a simple and concise method for expressing the ambient water quality of Oregon's streams for general recreational use, including fishing and swimming. The OWQI, originally developed in the 1970s, has been updated based upon improved understanding about water quality behavior. This report describes the historical basis of the OWQI and defines the improved design of the present OWQI. The index allows users to easily interpret data and relate overall water quality variation to variations in specific categories of impairment. This report demonstrates the value of the OWQI in presenting spatial and temporal water quality information. The OWQI improves comprehension of general water quality issues, communicates water quality status, and illustrates the need for and effectiveness of protective practices.