One and two-dimensional box models were used to estimate steady state single and two-layer gravitational circulation, transport, and residence times for the Pocomoke River, a tributary estuary on the eastern shore of Chesapeake Bay. Vertical salinity distribution in the narrow deep river varied from well mixed to stratified, both spatially and temporally. Comparison of estimated freshwater inputs to ADCP transport calculations indicates that the surrounding wetlands have the capacity to store and release a substantial amount of water to the river. The models are particularly useful in defining steady-state concentration distributions of dissolved conservative substances entering the river at a given flux. Spring and late summer residence times varied with river flow, as expected, from 52 to 102 days. The exception was 395 days during the summer drought of 1999.