The Potomac River and Estuary from the second largest tidal tributary of the Chesapeake Bay, which includes at its mid-portion the large urban and suburban Washington DC area. The Potomac River basin was sampled for trace metals near its fall line at Chain Bridge, Washington DC, from October 1996 through August 1997, to determine its contribution to the metal loading of Chesapeake Bay, To characterize the river loadings during various flow regimes, the river was sampled (1) routinely, at base-flow, on monthly to bi-monthly intervals, and (2) intensively during a spring-storm, high flow event. The upper Potomac watershed was sampled twice at nine stations within the headwaters of the basin. In Washington DC, Rock Creek tributary was sampled on a monthly or bi-monthly interval during base-flow conditions. For comparison, the Potomac Estuary was sampled once each during the winter and summer of 1997. The field sampling, preparation and analysis of the trace metals used ultra-clean sampling methods. The samples were analyzed for both dissolved (<0.45 u) and particulate fractions for Al, As, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se (dissolved only), and Zn. The data are computed and compiled for (1) dissolved/particulate concentration distribution, (2) loadings using USGS discharge data, and (3) basin yields on an area specific basis for each watershed. The concentrations are compared to similar results from other Potomac and Chesapeake Bay tributary studies.