Estuary water quality data (chlorophyll a, salinity and turbidity) were accessed and collated from a wide range of sources in 2007/2008 to assist with the production of the 'Estuaries and Coastal Lakes' theme of the first round of NSW State of the Catchments (SOC) reports.; ; Data sources included NSW government departments, local councils, water supply authorities, universities and consultants. The original data were collected for a variety of reasons including:; compliance with environmental standards (ie assess the impact of STPs on receiving waters) ; SoE reporting; planning and management; research; ; The source data have been compiled into one Excel spreadsheet with 78 fixed format Excel worksheets, one for each estuary. Where provided the location of water quality monitoring sites is provided as a spatial dataset.; ; The method of data collection, units of measure, data quality, and period of record varies between data providers. Data were subjected to a quality assurance process before being accepted into the database. Some data are subject to agreement with the individual data providers and have been removed from the dataset.; ; The data were used for developing a new classification system based on the response of chlorophyll a to nutrient loading from the catchment. The classification system was then applied to defining reference condition, trigger values (chlorophyll a and turbidity) for management action and the extent of compliance of water samples with the trigger values.