Deepwater ocean outfalls: A sustainable solution for sewage discharge for mega-coastal cities (Sydney, Australia): Influences on beach water quality. (August 2019)

• Record Type: Journal Article
• Authors: Manning, S.S.; Dixon, J.P.; Birch, G.F.; Besley, C.H.
• Is Part Of: Marine pollution bulletin. Volume 145(2019)
• Page Start: 691
• Page End: 706
• Publication Date: 2019-08
• Subjects: Enterococci -- Faecal coliforms -- Recovery -- Shoreline -- Stormwater; Marine pollution -- Periodicals; Marine Biology -- Periodicals; Water Pollution -- Periodicals; Mer -- Pollution -- Périodiques; Publications périodiques; Pollution des mers; Lutte antipollution; Electronic journals; 363.7394
• DOI: 10.1016/j.marpolbul.2019.05.010
• Languages: English
• ISSNs: 0025-326X

Abstract

Abstract: Shoreline discharge representing approximately 80% of sewage generated by Sydney (Australia) was replaced with three deepwater ocean outfalls between 1990 and 1991. Beachwatch bacterial monitoring data collected between 1989 and 2016 were analysed to assess the impact of commissioning on bathing water quality along 32 km of coastline. Bacterial contamination was reduced by 26–99% during the first 32 months post-commissioning and in the longer post-commissioning period, 1993 to 2016, bathing water quality improved for 31 beaches. Relatively stable bathing water quality was observed for five other beaches after the 2001 upgrade of another shoreline wastewater treatment plant. Bacterial contamination of bathing water in this 24-year post-commissioning period was most influenced by rainfall in the 24-h to 9 am on the day of sampling. Bacterial contamination from surfacing shore-blown wastewater plumes was not evident, whereas stormwater-delivered bacterial contamination was apparent and varied between beaches. Graphical abstract: Unlabelled Image Highlights: Installation of three ocean outfalls reduced bacterial contamination along 32 km of coastline. A marked decline in human health illness-risk followed inauguration of outfalls. Over the 24-years after ocean outfall installation all-weather bathing water quality improved. Poor bathing water quality is now related to rainfall in the period 24-h to 9 am before sampling. Contaminated stormwater still impacts bathing water quality, albeit at a lower level.