Yuen Long District (East) (Map)
In the eastern region of Yuen Long District, there are two major watercourses, namely, Kam Tin River and Ngau Tam Mei Main Drainage Channel. There are also a few minor streams that flow across San Tin (e.g. the areas of Shek Wu Wai and Ki Lun Tsuen) and Ta Shek Wu respectively.
The pollution of the above watercourses is mainly caused by occasional illegal discharges from livestock farms and unsewered developments in the catchment of individual watercourses.
Livestock farms are mainly located within the catchment of Kam Tin River and the areas of Shek Wu Wai and Ki Lun Tsuen.
Kam Tin River
The Kam Tin River is the largest natural drainage system in the eastern region of Yuen Long, although some sections of the river have been concreted and widened as a measure for flood prevention. The 50 km Kam Tin River covers a catchment area of about 44 km2, which is bounded by Kai Kung Leng to the north, Tai To Yan to the east and Tai Mo Shan to the southeast. Flowing from southeast to northwest, Kam Tin River has two main branches, one to the north and the other to the south, which merge near Ko Po Tsuen before joining the main drainage channel leading to inner DeepBay. Two tidal barriers, in the form of inflatable dams, are located downstream just before the two branches merge, and water upstream of the dams is pumped downstream by a pumping station operated by the Drainage Services Department. River sections downstream of these dams are subject to tidal influence. Discharge from livestock farm is one of the suspected pollution sources of Kam Tin River.
Ngau Tam Mei Main Drainage
The Ngau Tam Mei Main Drainage Channel was one of the river training projects for alleviating the problem of severe flooding in the lower and middle parts of the Yuen Long, Kam Tin and Ngau Tam Mei Basins. The upstream and downstream portions of the project were completed in 2003 and 2005 respectively. Running from east to west, the Channel covers a catchment area of about 10 km2 with an inflatable dam at the downstream end of drainage channel that prevents tidal water intruding into the channel. The suspected major water pollution sources within the catchment are discharges from the livestock farms and rural unsewered villages draining into the channel.
San Tin
San Tin is a broad area in the Northwest New Territories and is significantly urbanized in recent years, which is bounded by the Shenzhen River to the north, Lok Ma Chau to the east, Ki Lun Shan to the southeast and Mai Po the west. There are many unsewered villages scattered at San Tin and the livestock farms are more concentrated at its southern region, such as the Shek Wu Wai and Ki Lun Tsuen areas. San Tin has no large stream course while there are a few small ones flowing across its Shek Wu Wai and Ki Lun Tsuen areas. Livestock waste is the most significant pollution source.
