Water quality management of aquifer recharge using advanced tools Valentina Lazarova, Yves Emsellem, Julie Paille, Karl Glucina and Philippe Gislette ABSTRACT Managed aquifer recharge (MAR) with recycled water or other alternative resources is one of the most rapidly growing techniques that is viewed as a necessity in water-short areas. In order to better control health and environmental effects of MAR, this paper presents two case studies demonstrating how to improve water quality, enable reliable tracing of injected water and better control and manage MAR operation in the case of indirect and direct aquifer recharge. Two water quality management strategies are illustrated on two full-scale case studies, including the results of the combination of non conventional and advanced technologies for water quality improvement, comprehensive sampling and monitoring programs including emerging pollutants, tracer studies using boron isotopes and integrative aquifer 3D GIS hydraulic and hydrodispersive modelling. Valentina Lazarova (corresponding author) Julie Paille Karl Glucina Philippe Gislette Suez-Environment, 38 rue du président Wilson, 78230 Le Pecq, France E-mail: valentina.lazarova@suez-env.com Yves Emsellem Watermodel, 10 rue Lémeray, 06600 Antibes, France Key words | aquifer recharge, emerging pollutants, modeling, tracers of recycled water, water quality control INTRODUCTION Artificial recharge of aquifers can be defined as a stimulated transfer of surface or recycled water within a ground media thanks specific installations and adjustments of infiltration. Artificial recharge of aquifers is a quite recent technique that had been developed between 1950 and 1960 in several countries: United States (Los Angeles 1952), Netherlands (Amsterdam 1955), Germany (Berlin 1954), and France (Croissy 1959). During the decade, aquifer recharge with recycled water is becoming one of the most rapidly growing water reuse applications (Dillon et al. ; Dillon & Jimenez ). The main purposes of groundwater recharge are to stop declining levels of groundwater, protect coastal aquifers against saline intrusions, provide inexpensive storage and transportation of recharged water, ameliorate problems of land subsidence, as well as to improve water quality. Suez Environnement has operated and investigated artificial recharge (AR) for more than 40 years in several sites to achieve sustainability in overdown aquifers enabling a large number of quality, quantity and ecological surveys to be carried out. In France, artificial recharge from surface water to groundwater applies to the two largest groundwater schemes supplying the West of Paris Area in France (Figure 1): Croissy sur Seine (300,000 m 3 /d), Flins Auber- genville (150,000 m 3 /d), the Chalk aquifer of Moulle (80,000 m 3 /d), and finally, the alluvial aquifer of Poncey lès Athées (60,000 m 3 /d). In California, direct recharge with high quality recycled water has been performed since 1995 into the West Coast Basin aquifer to stop salt intrusion. To date, nearly 11,2 million m 3 per year of recycled water has been recharged, replenishing the basin with a cost effec- tive, reliable, and high quality water to help make up the pumping overdraft that exists. Several R&D programs have been performed to better control and optimise salt intrusion barrier, as well as to investigate water quality evol- ution and residence time of recycled water (Levine et al. ; Lazarova et al. ). One of the major challenges of aquifer recharge is the estimation of mixing of introduced new water and its pen- etration into the natural groundwater system. According to the resultants of a number of recent studies, environmental isotopes are considered as a reliable tool for control of 1161 © IWA Publishing 2011 Water Science & Technology | 64.5 | 2011 doi: 10.2166/wst.2011.418