1 Susceptibility of Alwahat Groundwater to Contamination by Produced Water Disposal Salem Elsakran Vice-deanship for Academic' Affairs, Faculty of Engineering & Petroleum-Galo P.O. Box 1308, Benghazi University, Benghazi, Libya E-mail: salem.agela@uob.edu.ly, Mobile: +218 913828744 Keywords: Produced Water Disposal, Groundwater Pollution, Groundwater Flow Direction, Groundwater Extraction, Groundwater Drawdown, Hydro-Geological Sitting, Abstract Vast areas of Alwahat region (more than 1500 Acres) are produced water disposal sites, as a result of oil separations, these areas are distributed in many locations with high risk of groundwater pollution, due to downward percolations of disposed pollutants. The risk of contamination is stimulated by many factors such as, the high permeability of the aquifers laying underneath, low topography in contrast with the surroundings, high groundwater extraction, shallow water table, high salt content, toxic substance in the disposed water, south to north (natural/induced) groundwater flow direction, towards Alwahat region, limited produced water treatment, limited water injection (pressure maintenance) projects, old separation facilities, limited separation capacity, absence of natural or artificial lining in the disposal bits and absence of effective legislations. This paper describes the vulnerability of groundwater, especially of groundwater supplies, to existing or potential sources of contamination due to continuous disposal of produced water on land, which has relatively high capacity to assimilate the pollution load and has a high risk of deteriorating the quality of groundwater, especially in shallow open wells surrounding the oil fields. Introduction Oil industry disposal of produced water on land and the subsequent pollution of groundwater and soil of surrounding urban farmlands of Alwahat region is a common, old and currently regular practice of many oil fields. Recently and because of big scale of this practice and high toxicity of disposed water, the issue became politically sensitive with social, economic and national security dimensions in the region with population (as of year 2010) exceeding 33810 resident, growth rate of 1,78 % and the general land use adjacent to the oil fields disposal/spills sites is devoted to farming. Aspects of oil produced water disposal have not been studied as extensively as domestic sewage disposal practices, at least for a developing country like Libya. Many oil fields in the region, dispose their effluents on shallow bits at the land surface. The salt content of the soil has started building up slowly and the adjacent farmlands shallow open wells might get polluted. This study attempts to capture the possible environmental impacts of produced water disposal in the region.