The Environmental Protection Department is stepping up the monitoring of beaches with rubbish problems. It will take water samples weekly.

Noting the grading of some beaches has remained unchanged, with St Stephen's Beach upgraded from 'poor' to 'fair', the department said there might not be any direct correlation between floating refuse and deterioration in the bacteriological water quality.

Swimmers should be cautious and refrain from swimming in places with lots of refuse.

Water quality at 10 beaches has been rated 'good' for this weekend, 15 'fair' and eight 'poor', according to the department's latest grading.

Clear Water Bay First Beach has upgraded to good from fair. But Chung Hom Kok, Deep Water Bay, Lower Cheung Sha and Stanley Main Beaches have fallen from good to fair, while Cafeteria New, Golden and Shek O Beaches have dropped from fair to poor.

The department said the changes are generally within the normal range of fluctuation of the bacteriological water quality of the beach. Anglers', Approach, Ting Kau, Casam, Gemini, Hoi Mei Wan and Lido Beaches are closed to swimmers year round because of poor water quality.

As many beaches are likely to be more polluted than their grades suggest during and after periods of heavy rain, bathers should avoid beach swimming for up to three days after a storm or heavy rain. See the department's website or call 2511 6666 for more information.