Detailed geochemical investigation of the bottom sediments in Port Kembla Harbour using neutron activation (NAA) and X-ray-fluorescence (XRF) techniques has delineated areas severely impacted by anthropogenically-sourced trace elements including potentially toxic metals (Pb, Cu) and metalloids (As and Se). In the south western section of Port Kembla Outer Harbour, copper concentrations in excess of 6000 ppm (~30x ANZECC-ARMCANZ (2000) ISQG-high trigger value) are associated with significant (i.e. above ISQH-high) concentrations oflead, zinc and arsenic. The potential source of sediment contamination here is the Port Kembla Copper (formerly ERS and Southern Copper) smelter. Port Kembla Inner Harbour sediments are geochemically distinct from those in the Outer Harbour being generally characterised by lower gold, zinc, copper and lead values and below detection limit (5ppm) concentrations of selenium. Locally very high (20%wt) concentrations of iron, zinc (>2000ppm) and tin (1500ppm) are suggestive of inputs from BHP Steel. The depths to which sediment contamination extends are not firmly established but are at least 50cm in sections of the Outer Harbour. Trace element contaminants are generally concentrated in the finer (62._5j.lm) sediment fraction, however, significant contamination also is evident in the courser (62.5-250j.lm) sediment fraction suggesting that at least some trace elements have an association with industrially-sourced particulate matter. Stable lead isotopic studies indicate the existence of and potential mixing of two major sources of anthropogenic lead in Port Kembla Harbour. Lead in the Outer Harbour has 206/204Pb of 17.5-17.8 (208/206Pb 2.13-2.09), close to that of recent Southern Copper emissions whereas Pb in the Inner Harbour has 206/204Pb of 18.0-18.6 (20S/206Pb 2.09- 2.03) generally consistent with a steelworks source. Future management of this contaminated sediment will need to address issues including disturbance, that is the potential for acid generation from pyrite decomposition and appropriate methods of disposal.