If a controversial artificial beach proposed for Tai Po were to open today, it would be the dirtiest beach in the city.
Environmental officials, however, say a proper sewage system in the Lung Mei area, now under construction, will make the water safe enough for swimmers by the time the facility opens.
Between 2000 and last year, the water quality at the site of the proposed beach deteriorated from "good" to "very poor", Environmental Protection Department data shows.
By comparison, the water at several closed beaches in Tsuen Wan improved significantly in the same period, enough to allow the government to reopen them.
The cleanest beaches in the city, Trio and Hap Mun Bay in Sai Kung, record two parts of Escherichia coli bacteria per 100 millilitres of water.
Lung Mei registered an E. coli count of more than 2,000 per 100ml at the start of the year. The high count meant more than 15 out of 1,000 swimmers would fall victim to skin and gastrointestinal illnesses, the department said.