To improve management of the environment, governments and managers need to know what other researchers and agencies have found and how they have found it. Accurate data and transparent methods are needed for governments to make good policy decisions and for the general public. Providing a comprehensive understanding of nutrient and pollutant loads into the marine environment around Australia is difficult given the different sampling and reporting requirements.

The aim of the National Outfall Database (NOD) was to facilitate cross-institutional data sharing among federal, state, local governments and the community to promote transparency and openness of governance for managing pollutants from WWTPs. The NOD also provides data and information that could be helpful for integrating infrastructure planning and decision making of sewage effluent impacts on marine environment. This categorizes outfall types and summarizes data collection from water treatment authorities for each outfall type. Of the seven states and territories examined there were 42 WTAs and 181 outfalls. Queensland has the highest number of WTAs at 18 followed by NSW at 12 and Victoria at 8. Water quality parameters monitored at each of the outfall sites varies and depended on the conditions set out in the Environmental Protection Authority licenses. However, at all sites, nutrient concentration and flow rates were reported. NOD data collection has been running since 2015. After the fourth year of data collection (2018) most WTAs (98%) have met these basic criteria for supplying the data. The data collection is comprehensively presented in a public database which facilitates transparency and data sharing among water treatment authorities, government agencies and the general public.

Promoting the transparency of monitoring data and pollutants entering the marine environment is important for managing marine biodiversity. This report highlights several needs and challenges that have been overcome and that still need to be addressed in order to provide easily accessible data and help promote insight-driven decisions and reduce pollutant impacts to the marine environment.