Field exploration, sampling, laboratory tests, and numerical simulations were conducted to study the impacts of the spatial variability of hydraulic conductivity of the bottom stratum of a reservoir on solute transport in groundwater. A case study was carried out in the Beidagang Reservoir, in Tianjin City. The results are as follows: the hydraulic conductivity of the bottom stratum of the Beidagang Reservoir was at a low level and showed a large spatial variability; the flow flux in the groundwater increased with the hydraulic conductivity and the impact of the average value of the hydraulic conductivity on the flow flux was greater than the standard deviation; inhibited by the groundwater flow, the solute transport weakened when the average value of the hydraulic conductivity increased; and the solute transport intensified when the spatial variability of the hydraulic conductivity increased because of relatively weaker groundwater flow.