Groundwater movement in naturally fractured and heterogeneous porous aquifers is highly complex, due to a strongly varying velocity field with multiscale correlation lengths. A key problem is how to describe tracer and contaminant movement in such systems. Realistic quantification of this movement is complicated by the uncertainty in characterization of aquifer properties. CTRW theory accounts for the often observed non-Fickian (or scale-dependent) dispersion behavior that cannot be properly quantified by using the advection-dispersion equation. The solutions provided here are valid for a wide range of transport regimes and dispersive behaviors.