WATER pollution has reached critical levels and will threaten public health this summer, environmentalists said yesterday. The Environmental Protection Department's report shows a downward trend in the water quality at beaches throughout the territory. Four gazetted beaches - Anglers', Castle Peak, Old Cafeteria, and Rocky Bay - are closed to swimmers. Last year at this time, only three beaches were closed. 'It is critical we do not have another cholera outbreak, more red tides, or increased hepatitis,' said Friends of the Earth chairman Mei Ng Fong Siu-mei. Government officials say the downward trend in water quality will continue until the first stage of the Strategic Sewage Disposal Scheme is completed in 1997. 'During the 1980s water quality improved, but that trend is in reversal,' department principal officer Dr Malcolm Broom said. 'That is why it is essential that the scheme be put into place as soon as possible.' Ms Ng also complained the Government was ignoring the rubbish and livestock waste which are considered major contributors to water pollution. Nine beaches were rated poor, two were very poor and six fair. The grades indicates the health risk for gastrointestinal disease and minor skin infections per 1,000 swimmers. The health risk for poor beaches is no more than 15 cases of minor illness per 1,000 swimmers, but very poor beaches have higher E coli counts. 'Bathers should avoid swimming at such beaches for two to three days after a storm, or even longer if the weather remains overcast, shorter if there is strong sunshine,' Dr Broom said. Hong Kong South: Big Wave Bay, poor; Chung Hom Kok, good; Deep Water Bay, good; Hairpin, good; Middle Bay, good; Repulse Bay, good; Shek O, fair; South Bay, good; St Stephen's, good; Turtle Cove, good; Stanley Main, fair; Rocky Bay, closed; To Tei Wan (non-gazetted), good. Tuen Mun District: Golden Beach, poor; Old Cafeteria, closed; New Cafeteria, poor; Castle Peak, closed; Kadoorie, poor; Butterfly, poor. Sai Kung District: Campers, good; Clear Water Bay 1st Beach, good; Clear Water Bay 2nd Beach, good; Hap Mun Bay, good; Kiu Tsui, good; Pak Sha Chau, good; Silverstrand, fair; Trio (Hebe Haven), good. Islands District: Cheung Sha Upper, good; Cheung Sha Lower, fair; Discovery Bay (non-gazetted), fair; Hung Shing Yeh, good; Kwun Yam Wan, good; Tong Fuk, good; Lo So Shing, good; Pui O, good; Silvermine Bay, fair; Tung Wan, Cheung Chau, good; Tung O (non-gazetted), good. Tsuen Wan District: Anglers', closed; Approach, very poor; Casam, poor; Gemini, poor; Hoi Mei Wan, poor; Lido, poor; Ting Kau, very poor; Tung Wan, Ma Wan, fair.