Groundwater flow around three hypothetical flow-through lakes, located in the upper, middle, and lower portions of a watershed, was numerically simulated in cross section under steady state and transient conditions. Results showed that (1) groundwater fluxes into and out of the lake located in the lowest position were higher and more stable than for lakes farther upgradient, and (2) periods of intense groundwater recharge caused flow reversals and the formation of a stagnation point downgradient of the uppermost lake, thereby causing a net increase in groundwater inflow. These simulation results provide guidance on monitoring network design, including the frequency of monitoring and/or sampling. ¿ American Geophysical Union 1994