What is the state of water quality of Victoria Harbour?
For the Victoria Harbour Water Control Zone, the compliance rate with the relevant WQOs in 2012 was 77%. Non-compliance was mainly found with regard to the Total Inorganic Nitrogen (TIN) objective at several monitoring stations. This could be due to a higher background TIN level under the influence of Pearl River discharge, as reflected in the increase in TIN levels at many stations in the northwestern and southern waters of Hong Kong, the year-to-year normal range of fluctuation of the discharge from surface run-offs, as well as the untreated sewage discharged from the four preliminary treatment works located between North Point and Central. After the commissioning of HATS Stage 2A, the pollution load to Victoria Harbour will be reduced when sewage from the PTWs is collected for treatment at the Stonecutters Island Sewage Treatment Works.
What is the Harbour Area Treatment Scheme?
The Harbour Area Treatment Scheme is an overall sewage collection, treatment and disposal strategy for areas on both sides of Victoria Harbour.
What is the progress of HATS Stage 2A?
The flow turning process under HATS Stage 2A commenced in September 2015. The facilities are scheduled to enter full operation within 2015.
Will the implementation of HATS 2B result in an observable improvement of the quality of the coastal waters?
The implementation of HATS 2A has already brought about the most significant improvements to main water body and water quality (WQ) of Victoria Harbour. The additional benefits that implementation of HATS 2B will bring about to the WQ of Victoria Harbour are the level of DO would be marginally improved and the levels of phosphorous and un-ionised ammonia would be reduced. However the level of total inorganic nitrogen would be increased due to the nitirification process of the sewage treatment.
The improvements will mainly be found in the western part of Victoria Harbour/around the HATS outfall area, away from the main activity areas of the community and will not result in an observable improvement of the quality of coastal waters due to the residual pollution discharges into the urban coastal waters, i.e. those not collected by our sewerage system due to various factors such as drain misconnections, and polluted surface run-offs from streets etc., the odour and visual impacts caused by near shore pollution to our urban coastal waters are still present.
Where are the pollution black spots in coastal areas of Victoria Harbour?
The water quality of some areas along both sides of Victoria Harbour has been subject to frequent complaints. These include the waterfront in West Kowloon, Hung Hom Promenade, Kai Tak, Wanchai ferry Pier, etc.
Is there an objective reference to measure quality of the coastal waters of Victoria Harbour?
The elimination of aesthetic and odour problems is our target in enhancing quality of the coastal waters. While aesthetic and, to an even greater extent, odour problems and their improvement would be difficult to quantify per se, we may draw reference from the E.coli level which is a common bacterial indicator of water pollution and is counted for compliance with the Water Quality Objective (WQO) for bathing beaches and secondary contact recreation subzones.
Though there is no known scientific literature or report to directly link the foul odour detected in environmental water samples with high levels of E.coli, if organic matter such as sewage is discharged into the storm drain system, the anaerobic decomposition of the organic sediments under anoxic (e.g. no-oxygen) condition may generate hydrogen sulphide and hence bad smell, which may be released through openings and manholes of the storm drains, and culvert outlets at the waterfront when the sediments are exposed to air under low tide condition. And, the levels of E.coli in near shore water can indicate whether the “source” of the odour problem detected in a certain area is sewage-related.
We would take into account relevant indicators of water pollution in seeking improvement to the water quality in different areas, such that the aesthetic and odour problems would be resolved.