Clean 2008, 36 (12), 0000 – 0000 M. Al Kuisi et al. 1 Mustafa Al Kuisi 1 Taiseer Aljazzar 2 Thomas Rüde 2 Armin Margane 3 1 University of Jordan, Department of Applied Geology and Environment, Amman, Jordan. 2 Department of Engineering Geology and Hydrogeology, RWTH Aachen, Aachen, Germany. 3 Federal Institute for Geosciences and Natural Resources (BGR), Hanover, Germany Research Article Impact of the Use of Reclaimed Water on the Quality of Groundwater Resources in the Jordan Valley, Jordan The use of reclaimed water and its impact on groundwater quality in the middle and southern parts of the Jordan Valley are investigated. The chemical analyses indicate that nitrate and bacteriological pollution is widespread, and thus, seriously affects groundwater use. During the study, 365 water samples were collected from wells and springs to determine the water chemistry and the extent of nitrate pollution. Three hydrochemical facies are identifed, i. e., (Ca – (Mg) – Na – HCO 3 ), (Ca–Na–SO 4 – Cl) and (Ca – Na – Cl). The change of facies is accompanied by a gradual increase in the ground- water total dissolved solids (TDS), which is mainly controlled by evaporates and carbo- nates dissolution in the aquifer matrix. Water analyses indicate that the shallow aqui- fer in the study area is affected by non-point pollution sources, primarily from natu- ral (manure) and chemical nitrogen (N)-fertilizers and treated wastewater used for agriculture. The concentration of nitrate in the groundwater ranges from 10 to 355 mg/L. Considerable seasonal fluctuations in groundwater quality are observed as a consequence of agricultural practices and other factors such as annual rainfall distri- bution and the Zarqa River flow. The noticeable levels of total coliform and Escherichia coli in the northern part of the study area may be attributed to contamination from the urban areas, intensive livestock production, and illegal dumping of sewage. Heavy metal concentrations in all samples were found to be significantly lower than the permissible limits for drinking water standards. Keywords: Bacteria; Escherichia coli; Fertilizers; Groundwater; Nitrate; Reclaimed water; Water quality; Received: December 12, 2007; revised: July 26, 2008; accepted: August 1, 2008 DOI: 10.1002/clen.200700190 1 Introduction Wastewater has been used for irrigation in Jordan for several deca- des [1]. Some treated effluent has been used directly on restricted crops of relatively low value, but the main practice has involved dis- charging the effluent to the environment where it mixes with fresh- water flows before being used indirectly downstream [2]. With dropping per capita freshwater availability, the increasing dominance of wastewater in the water balance, insufficient waste- water treatment capacity, and the need to protect domestic and export produce markets as well as local riparian water rights, the management of water reuse and enforcement of existing regula- tions have become increasingly important [2]. Nitrate contamination in shallow aquifers is a common problem in rural regions around the world [3 – 6]. Nitrate in groundwater originates largely from a variety of domestic and agricultural practi- ces and is typically found in oxygenated groundwater where nitrate is relatively stable and mobile. 1.2 Study Area The study area is located in the middle and southern part of the Jor- dan Valley between Wadi Rajeb in the north and the Dead Sea to the south, see Fig. 1. It covers an area in the Jordan Valley that is 45 km long and 3 to 10 km wide, and the area is bordered in the east by the escarpment of the eastern highlands. This escarpment, formed by lime- and sandstone plateaus, borders the valley all along its course [7]. Since the escarpment and the eastern highlands are divided by deeply incised east-west orientated streams, i. e., side wadis, this area is also called the Side Wadi Basin. East of the study area, these streams include (from north to south): Wadi Rajeb, Zarqa River, Wadi Shueib, and Wadi Kafrein. The flow in these wadis is fed by groundwater recharge from precipitation in the eastern highlands. The King Talal Dam reservoir (KTR) is fed by wastewater effluent from four wastewater treatment facilities, i. e., Khirbet As Samra (treatment plant for Amman and Zarqa), Jarash (east), Baq'a, and Abu Nuseir. The main tributaries of the Zarqa River (the second larg- est river in Jordan) are the intermittent Wadi Dhuleil, which drains the eastern parts of Amman-Zarqa Basin, and the perennial Seil el Zarqa, which drains the western parts of Amman-Zarqa Basin. The confluence of these rivers is at Sukhna, which defines the beginning of the Zarqa River. Correspondence: Dr. M. Al Kuisi, University of Jordan, Department of Applied Geology and Environment, P.O. Box: 13437 Amman-11942, Jor- dan. E-mail: mkuisi@ju.edu.jo i 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.clean-journal.com