Delta-wide pollution effort needed: expert

PUBLISHED : Monday, 29 September, 2008, 12:00am
UPDATED : Monday, 29 September, 2008, 12:00am

A marine scientist has urged the administration to step up cross-border efforts to improve water quality in the Pearl River estuary, which in turn would make Hong Kong's harbour cleaner.

Paul Harrison, director of the Atmospheric, Marine and Coastal Environment Programme at the Hong Kong University of Science and Technology, said a sewage treatment scheme would not alone improve water quality around Victoria Harbour without cross-border co-operation.

The scheme, started in 2001 to remove phosphorus and other material from sewage, was offset by the nitrogen influx from the Pearl River estuary, he said. Rainy summers bring more river discharge, flushing untreated sewage from livestock farms into the delta and making waters west of the harbour dirtier.

Dr Harrison said his research team had found excessive nutrients led to blooms of green algae, which could cut oxygen levels. Environmental Protection Department data shows that water quality around Deep Bay was very poor in 2006, ranking the dirtiest in the city.

Dr Harrison said it would not be cost effective to remove nitrogen from the water, which the government is planning to do in the next stage of the scheme that is to follow a review of the first stage in 2010. The improvement and construction work planned for the second stage will cost HK$10.8 billion, with annual operating costs of HK$700 million.

Dr Harrison said a cross-border effort would be better.

'Governments in Hong Kong and Guangzhou have been jointly monitoring water quality, but they need to accelerate in treating sewage from polluting sources such as chicken farms,' he said.

Meanwhile, the government has said drinking water is of good quality. Director of Water Supplies Ma Lee-tak said a management programme had been implemented to prepare the city for acute climate changes or a decrease in rainfall.

The programme includes exploring new water resources such as desalination, producing reclaimed water for toilet flushing, irrigation and other non-potable uses, and conservation, such as replacing ageing mains to reduce leakage.

Hong Kong was also aiming to form stronger partnerships across the delta to promote sustainable water use, he added.