Controlling Water Pollution

The EPD monitors water quality in rivers, streams, beaches and marine waters, and aims to ensure they meet healthy levels. In 2002 a major achievement was the long-awaited improvement in water quality in Victoria Harbour, following the completion of the first stage of the Harbour Area Treatment Scheme (HATS). The gains were widely spread throughout the harbour area, although the eastern portion benefited most.

Photo showing water quality is monitored regularly


Water Quality Monitoring

In 2002, 87 per cent of samples from marine monitoring stations met the overall compliance requirements for the Water Quality Objectives (WQOs), compared with 79 per cent in 2001. This marked increase was mainly due to a significant improvement in water quality in Victoria Harbour, as the first stage of HATS came into operation in 2002. The results for rivers and streams showed 82 per cent of monitoring stations met the WQOs, which was similar to that in 2001 (81 per cent). Among the beaches monitored by the EPD, 33 of the 41 gazetted beaches (80.5%) met the WQOs for bathing water in 2002. The number of beaches graded "good" increased by 2 to 23. However, the number of "very poor" beaches also increased, from two in 2001 to six in 2002. The number of "poor" beaches decreased from five to two. The deterioration occurred in beaches of the Tsuen Wan District near the western harbour, where the effluent from Stonecutters Island is concentrated. The situation is expected to improve once further stages of the Harbour Area Treatment Scheme are completed.

We typically measure physical and chemical parameters in our monitoring, but we are also interested in applying biological indicators in assessing the impact of pollution . These have been used for the contaminated mud disposal site at East Sha Chau and the results indicate there has been no trend of increasing contaminant burden in target species collected in the subject area. In 2001 we began a study to examine how we could extend biological indicators to the long-term monitoring of marine pollution and environmental health. We expect to complete the study in June 2003.


Harbour Area Treatment Scheme (HATS)

The first stage of HATS completed its first full year of operation in late 2002, with positive results. This stage involves collecting sewage from Kowloon and eastern Hong Kong Island and applying chemically-enhanced primary treatment at Stonecutters Island, which removes approximately 50% of the total organic pollution loading. This has had a widespread beneficial impact on water quality. Compared with 2001, bacteria levels have dropped by about 90% in the eastern harbour, ammonia levels have dropped by 50-60% and dissolved oxygen has increased by 20-30%. The improvements extend through the central harbour and up into the Rambler Channel where, at the northern end, bacteria decreased by about 60% and dissolved oxygen rose by 20%. Dissolved oxygen also rose by about 10% in the western harbour. However, as expected, there was a deterioration in bacterial levels (increases of 55-135%) and ammonia (increase up to 26%) in areas directly surrounding the outfall itself. To reverse these changes, it will be necessary to pursue the further stages of HATS.

Map showing water quality improvement after commissioning of HATS Stage I

Photo of Stonecutters Islands Swage Treatment Works

The remaining HATS stages require community agreement on the level of treatment, location and cost. An International Review Panel of HATS recommended in November 2000 that the level of treatment be raised and that the treated effluent be discharged within the harbour. The government is testing the effectiveness of alternative treatments, including biological aerated filter. A major study is also underway on the environmental and engineering feasibility of four location options recommended by the panel. The options are to conduct all treatment at the existing Stonecutter's Island plant, build two plants at Stonecutter's and Lamma Island, build two plants at Stonecutter's and Sandy Bay, or build three plants at Stonecutter's, Sandy Bay and North Point. A study was also commissioned in 2002 to investigate the benefits of private sector participation in sewage treatment. The studies should be completed in 2003 and the results will be released to the public.

Meanwhile, a consultation on the proposed water quality criteria for HATS resulted in a consensus. The consultation involved concerned stakeholders such as academics, green groups and learned societies. The consultation resulted in more stringent requirements for dissolved oxygen, especially in sensitive areas, and adjustments to nutrient criteria to reflect observed background levels and the potential importance of phosphorus in promoting algal blooms.


Other Sewage Work

Sewerage master plans have been reviewed to take into account projected population increases up to 2016. In light of revised population forecasts and development proposals, the review of sewerage master plans for Central and East Kowloon, Tuen Mun, Tsing Yi and the Outlying Islands proposed upgrading works in these areas. Similar reviews on the need for additional services for Hong Kong Island, North District and the Tolo Harbour area are expected to be completed in 2003. Further reviews will be undertaken if the need is identified by planning studies.

Apart from sewerage master plans, a study on urban stormwater pollution control focusing on the West Kowloon area will be commissioned in 2003, and will recommend appropriate management and control measures.

Treated and disinfected effluent can be re-used in such things as flushing, landscape irrigation and vehicle cleaning

Two proposals concerning water pollution control legislative amendments could not be carried forward as planned. One concerned proposed new effluent standards, which are generally supported by scientists and green groups but have been opposed by some commercial and industrial sectors. The feasibility of promulgating the new standards is now under consideration by our policy bureau. Opposition also greeted a proposed amendment to the Water Pollution Control Ordinance to close loopholes, create heavier fines and make some provisions more business-friendly. In light of the public comments received, the EPD revised some of the proposed legislative amendments and these were being considered by the policy bureau at the end of 2002.

An effluent re-use demonstration scheme is being planned for a government sewage treatment plant in the North District area. The reclaimed water will be used mainly for toilet flushing purposes. Proposals for the scheme are being drawn up, with a view to commence the demonstration scheme in 2004. Another trial scheme will be carried out at Ngong Ping on Lantau Island, where reclaimed water will be supplied from the new sewage treatment plant in 2005 for flushing and other possible uses.

Regional Efforts

Hong Kong and Guangdong have had on-going co-operation and exchanges on regional water pollution control for common water bodies since the early 1990s. Under the Deep Bay Water Pollution Control Joint Implementation Programme (JIP) established in 2000, the Hong Kong and Shenzhen governments are reducing the pollution load to Deep Bay, with a view to restoring the water body to a clean and healthy state by 2015. The JIP will be reviewed jointly by both governments every five years. In 2002, both sides reached an in-principle agreement to exchange information on Deep Bay's water pollution control programmes on a regular basis and to advance the first JIP progress review.

Hong Kong and Shenzhen are also co-operating on a study of Mirs Bay. An inventory of pollution loads has been compiled by staff from the EPD and the Shenzhen Environmental Protection Bureau, to determine the sources and types of pollution entering the bay. This information was used to assess the pollution impacts and determine the bay's assimilative capacity. The study is at the final stage of evaluating alternative pollution control strategies and a recommendation on the regional water quality management plan for Mirs Bay will be available in 2003.

The Joint Working Group on Sustainable Development and Environmental Protection, which has representation from both Hong Kong and Guangdong, set up a Pearl River Delta Region Water Quality Protection Special Panel in 2001. Under the Special Panel, the two sides are working together to develop a numerical water quality model for the Pearl River Estuary, with the ultimate goal of formulating a joint water quality management plan for the estuary. In 2002, a project coordinator was appointed to provide technical support services for the project. A modelling specialist contractor and a data supplier will also be employed in 2003 to work on model development and data acquisition respectively.

In 2002, the EPD completed a marine monitoring method validation exercise with the State Oceanic Administration's (SOA) National Marine Environment Monitoring Centre, South China Sea Environment Monitoring Centre and Government Laboratory. The exercise was conducted to ensure the comparability of marine monitoring data between Hong Kong and the Mainland. Plans for Hong Kong's participation in the National Marine Environment Monitoring Network were under development pending the restructuring of the Network, to be finalised by the SOA.