Exploitation of excessive water may cause saltwater intrusion in coastal aquifers. In order to determine and prevent saltwater intrusion, the results of level and quality measurements together with the variations in underground waters at wells are evaluated and necessary measures are taken. The aim of this study is to evaluate the changes of electric conductivity (EC, dS/cm), total dissolved solids (TDS, mg/l) and chloride (Cl, mg/l) values observed in 23 underground water (UGW) wells located in Goksu plain, in July, 2002 by applying probabilistic and geostatistical methods. Kriging estimated maps are drawn and two dimensional variations of the parameters are investigated. It is concluded that the use of UGW wells at 40% of the studied area is inconvenient. As the seashore is approached, the levels of EC, TDS and Cl parameters are at threatening levels considering the sustainability of agricultural production.