XN000022-1995-04-26 — Page 56

(a)

(b)

43

The Tolo Harbour Action Plan (THAP) was put in place in 1987 to tackle water pollution and red tides in Tolo Harbour. The organic and nutrient pollution loads have been reduced by 45% and 36% respectively since the inception of the THAP. Much of these reductions is the result of enforcement action under the Water Pollution Control Ordinance, following declaration of the Tolo Harbour & Channels Water Control Zone in 1987, and of livestock waste control through the Waste Disposal Ordinance since 1988. Enforcement action and other measures have brought about a marked improvement in water quality, as indicated by lower densities of algae and a reduction in the number of red tides in recent years. Nevertheless, because some polluting inputs continue, red tides occur from time to time, especially in the spring when algal blooms are more likely to occur. Further improvement to water quality is expected as more sources of pollution are removed.

Effluent export from the Sha Tin sewage treatment works, a key part of the THAP, was commissioned in April 1995. The same will be done for the Tai Po sewage treatment works in August 1995. Overall, this scheme is expected to further reduce organic and nutrient loadings by 10% and 30% respectively. The works to provide 14 Sha Tin villages with new sewers are nearing completion and works to provide 25 villages in Tai Po with the same have already begun. Further reductions in Tolo Harbour's pollution loading will occur when domestic sewage from these villages is diverted to the public sewers.

These major improvement works, together with continued enforcement of the Water Pollution Control Ordinance to remove expedient connections and illegal discharges, the collection of leachate from the Shuen Wan landfill for treatment and restoration of the landfill upon its closure later in 1995, will also bring about further reductions in pollution loads.

Dredging the Tolo Harbour seabed would not help much. Although organic sediments on the seabed release nutrients, their contribution to red tides is small compared to the amount of pollution coming from land-based sources. Dredging the sediments would also lead to resuspension and dispersion of the nutrients and other pollutants into the water body. The most effective way to tackle water pollution in Tolo Harbour is to reduce pollution loads entering the water as outlined under (a) above.

End/Wednesday, April 26, 1995