Electrokinetic effects of water flow during pumping tests have been shown to generate surface Streaming Potential (SP) anomalies of several tens of mV that are well correlated with the geometry of the water table. It follows that SP measurements can be used to estimate aquifer hydraulic properties. We have developed an inversion scheme for surface SP data generated by flow pumping and found that we are able to estimate the hydraulic conductivity and the depth and the thickness of the aquifer. We applied our inversion scheme to the data from Bogoslovsky and Ogilvy <1973> and found a hydraulic conductivity of 10-5 m.s-1, an aquifer thickness of roughly 28 m and an electrokinetic coupling coefficient of -1 mV.m-1. These values are in the range of what is expected for this kind of environment.