Water quality monitoring will be carried out in the nearshore waters of the Great Barrier Reef to assess change over time in concentrations of key water quality indicators. Monitoring of marine water quality is required to establish the extent of improvement in lagoon water quality as a consequence of any reductions in delivery of pollutants to the marine environment. This monitoring will include the measurement of chlorophyll as a surrogate nutrient indicator, as well as the measurement of water turbidity and pesticide and pharmaceutically active compound concentrations at key inshore reef sites. Sampling methods will include state of the art water quality sensors with long-term data logging capacity to minimise fieldwork in the marine environment. Sampling of marine sediments will also be carried where necessary to assess long- term change in the accumulation of pesticides in the seafloor if these types of pollutants are being sequestered. Outcomes: Information about current status and long-term (10 year) trends in water quality and marine ecosystem status in the GBRWHA