Water quality at Deep Water Bay, Clear Water Bay Second and Golden beaches has been rated 'good' by the Environmental Protection Department for this weekend. Silverstrand Beach has been rated 'fair'.

There was no change in the grading of the four beaches compared with the previous week.

These four beaches are open year round, and all are equipped with shark nets. Other beaches are closed for the winter.

Beach grades can also be obtained from the department's homepage or the beach hotline, 2511 6666.

The department warns that many beaches are likely to be more polluted than their grades suggest during and after periods of heavy rain.

Bathers should avoid swimming at beaches for up to three days after a storm or heavy rainfall.

2 red tide cases seen

An inter-departmental working group reported today that two red tide sightings were reported on January 2.

Department officers found red tide in Shing Mun River while Leisure & Cultural Services Department officers observed another case at Deep Water Bay Beach. Both dissipated the following day.

The red tide in Sing Mun River was formed by Cylindrotheca closterium and Prorocentrum minimum, while the one at Deep Water Bay Beach was formed by Phaeocystis globosa.

Cylindrotheca closterium has not been sighted in Hong Kong waters before. Prorocentrum minimum is common and Phaeocystis globosa is rare here. All three species are non-toxic.