The flushing of littoral regions is governed by barotropic river flows, QR, and baroclinic exchange flows, ΔQ. This note presents field observations of two different flushing regimes in a shallow wetland that borders a lake. In spring, when river flows are high, the wetland circulation is river- or jet-dominated, ΔQ/QR1, that vary both on diurnal and synoptic (10--20 days) timescales in response to differential heating and cooling between the wetland and lake and to wind. These exchange flows can enhance wetland flushing by a factor of 10 relative to river flushing. A one-dimensional decoupled heat and flow model represents diurnal exchange flows in this system well and may be used to assess the importance of exchange flows in other systems. ¿ 2001 American Geophysical Union