Water Quality Assessment of Euphrates River Within Fallujah City Using Water Quality Indices Technique Ghadeer Jamal Hasham, Majeed Mattar Ramal * Dams and Water Resources Engineering, College of Engineering, University of Anbar, Ramadi 31001, Iraq Corresponding Author Email: majeed.mattar@uoanbar.edu.iq https://doi.org/10.18280/ijdne.170410 ABSTRACT Received: 21 March 2022 Accepted: 6 June 2022 Scientist and researchers were recognized the important of water quality, Water resources are especially susceptible aquatic systems to many pollutants sources. Determination of water quality characteristics are very significance in term of the environmental considerations. This study aims to assess the water quality of the Euphrates river in the Fallujah Euphrates Reach (FER) by measuring the concentration of chemical and physical properties of water using multiple devices. CWQI and WAWQI were also used to assess the quality of water and indicate its suitability for drinking purposes, based on standard specifications from IQS, WHO, and USEPA as a criterion for comparison purposes. The findings show that with the use of CWQI, the quality of water was fair based on IQS, good based on WHO, and marginal based on USEPA, while the quality ranged between good, poor, very poor, and unsuitable for drinking purposes as a result of using WAWQI, with the exception of station 7, where the value of the WAWQI was greater than 100 mg/L, which indicates that the water is not suitable for drinking purposes as a result of the pollution of this station from a point source, which caused the high concentration of turbidity, sulfate, BOD5, and total dissolved solids, and decreased the DO concentration in this station compared to the rest of the stations, which were within the permissible. Keywords: water quality, assessment, WAWQI, CWQI, Euphrates, Fallujah city 1. INTRODUCTION Rivers are the most important component of water resources utilized to meet human requirements. Surface water quality should be researched from a quality standpoint due to the significant implications it has on the environment and human health [1]. Water quality is influenced by natural factors such as geology, climate, and hydrology, as well as manmade factors such as urban and agricultural drainage and industrial waste [2]. Iraqi rivers' water is becoming more threatened as a result of rising hardness, industrial, salinity, and agricultural pollution, and water scarcity due to climate change-reduced precipitation in the north part of Iraq, as well as poor irrigation planning and the numerous dams erected in Iran, Syria, and Turkey [3, 4]. In addition to the expected decrease in the amount of freshwater accessible in the future, Thus, surface water quality has become a key problem in recent years. Water quality may be determined by evaluating its chemical, physical, and biological qualities. Monitoring the sources of pollutants and attempting to avoid or reduce their impacts is one of the ways that may be used to keep Iraq's surface water safe [5-7]. One of the traditional methods of water quality evaluation involves comparing the observed values of water quality variables within water samples with an accessible reference guideline for the same variables. A large number of characteristics must be determined in order to determine the quality of river water. Even for experts on the topic of water, tabulating and interpreting these factors might be challenging at times. Furthermore, it may not necessarily give a full picture of the water quality situation or an integrated understanding of it. As a result, a variety of measures, such as water quality indexes, have been used to combat the problem. In 1965, Horton (1965) created the first numerical WQI model, which included eight parameters. Following the Horton index, a slew of other indexes have been established by various organizations and writers throughout the world. The original Oregon Water Quality Index and the National Sanitation Foundation Water Quality Index (NSFWQI), for example, were established in the 1970s and 1980s [8]. A WQI is a dimensionless number that works to unify the values of classification curves by integrating many water quality variables into a single number and enabling straightforward data monitoring analysis. The following are some of the advantages and applications of water quality indices: 1- Increasing the objectivity and decreasing the subjectivity of policy decisions 2-To provide a holistic picture of the source's overall quality so that non-technical stakeholders may grasp it. 3-To identify the differences in situations after and before the regulatory policy or law is implemented. 4: Comparing the quality of water from various sources and deciding on the best way to use the water resource at hand [9]. In addition to being one of the most successful methods for communicating information about water quality to concerned individuals and policymakers. As a result, it has become a crucial criterion for surface water evaluation and management. A WQI rating is a rating that reflects the combined impact of many water quality factors. The WQI is determined using the appropriateness of water for human consumption as a criterion [10]. Water quality data is crucial for implementing sustainable water management methods. Water quality is determined by the physical and chemical features of a sample of water, as well as International Journal of Design & Nature and Ecodynamics Vol. 17, No. 4, August, 2022, pp. 563-570 Journal homepage: http://iieta.org/journals/ijdne 563