A further challenge to Hong Kong's marine waters came in the form of mud.
This report is designed to offer a detailed picture of the monitoring programme and how it has developed over time, as well as outlining some of the improvements in Hong Kong's marine water profile that have been achieved over the last twenty years.
Bacteria, excessive nutrients, toxic chemicals and other pollutants can make swimmers sick, contaminate or kill marine life, and give off malodor.
With many of the local industries relocated to the Mainland in the last two decades, the key pollutants come from human sources and livestock farms in the rural area.
The water quality of most parts of Hong Kong's waters is relatively stable and generally slow to respond to specific sources of pollution. By contrast, Deep Bay to the west has strong estuarine characteristics, meaning the water there is mixed with river flow, is low in salinity, typically shallow averaging 4 to 10 metres in depthsilty and turbid.
Twenty years ago, thousands of factories-particularly in the Kwun Tong and Tsuen Wan areas-discharged their untreated industrial waste directly into sewers that flowed into the sea.
The Government is actively implementing infrastructure projects. Now, all sewage around Victoria Harbour receives chemically-enhanced primary treatment and disinfection.
Both sides are continuing to take forward cooperation and exchange on water quality management of the estuary according to the recommendations of the study.