The spatial distribution of the hydraulic conductivity is modelled by a power law, and we present a methodological approach to quantify the exponent (crowding index) of such a law as detected within a well-type flow configuration. Based upon the outcome of several pumping tests con- ducted into a caisson (mesoscale), we identify the crowding index as function of the volumetric flow rate. Hence, we develop a simple (although approximated) procedure to assess whether the spatial distribution of can be characterized by a power law. We demonstrate that, even at the mesoscale, the conductivity can not be regarded as a formation's property (nonlocality), in agreement with the recent developments on the theory of flows into radial configurations.