River Water Quality in Hong Kong in 2018 River WaterEnvironmental Quality in Hong Kong Protection Department 2018 The Government of the Hong Kong Special Administrative Region1 Mission To conduct a comprehensive and scientific monitoring programme that helps safeguard the health of Hong Kong’s rivers and streams and achieve the Water Quality Objectives. River Indus Disclaimer Whilst the Government of the Hong Kong Special Administrative Region ("the Government") endeavours to ensure the accuracy of the information in this report, the Government (including its officers and employees) makes no warranty, statement or representation, expressed or implied, with respect to accuracy, completeness, or usefulness of the information contained herein, and in so far as permitted by law, shall not have any legal liability or responsibility (including liability for negligence) for any loss, damage, injury and death which may result, whether directly or indirectly, from the supply or use of such information. Users are responsible for making their own assessments of all information contained in this publication before acting on it. Copyright Notice The information contained in this publication can be used freely for study, research and training purposes subject to acknowledgement of the source. Use of the information for purposes other than those stated above requires prior written permission of the Director of Environmental Protection. Acknowledgement We acknowledge the Government Laboratory for undertaking chemical analyses of the water samples. River Water Quality in Hong Kong 2018 2 Content 1. Introduction 2. An Overview of Hong Kong’s Rivers and Streams in 2018 2.1. Compliance Rate of Water Quality Objectives (WQOs) 2.2. Water Quality Index (WQI) Gradings 3. Water Quality State at Rivers and Streams 3.1. Eastern New Territories 3.2. Northwestern New Territories 3.3. Lantau Island 3.4. Southwestern New Territories and Kowloon List of Figures Figure 1 Overall WQO compliance in the river waters of Hong Kong, 1987-2018 Figure 2 WQO compliance for five key parameters in the river waters of Hong Kong, 1987-2018 Figure 3 Water Quality Index gradings for the river waters of Hong Kong, 1987-2018 Figure 4 Map of river monitoring stations and Water Quality Index gradings in 2018 Figure 5 Map of river monitoring stations and Water Quality Index gradings in 1987 Figure 6 Annual geometric mean E. coli levels for river waters of Hong Kong (1988- 2018) Figure 7 Map of river monitoring stations and levels of E. coli in 2018 (Annual geometric mean) Figure 8 Compliance with the Water Quality Objectives of the rivers and streams in the Eastern New Territories over the past three decades in percentage Figure 9 Water Quality Index gradings and E. coli levels in Shing Mun River Figure 10 Water Quality Index gradings and E. coli levels in Lam Tsuen River and Tai Po River Figure 11 Water Quality Index gradings and E. coli levels in Tai Po Kau Stream, Shan Liu Stream and Tung Tze Stream Figure 12 Water Quality Index gradings and E. coli levels in Tseng Lan Shue Stream Figure 13 Water Quality Index gradings and E. coli levels in Ho Chung River, Tai Chung Hau Stream and Sha Kok Mei Stream Figure 14 Compliance with the Water Quality Objectives of the rivers and streams in the Northwestern New Territories (North District and Yuen Long) over the past three decades in percentage Figure 15 Compliance with the Water Quality Objectives of the smaller streams in Northwestern New Territories (Lau Fau Shan area) over the past two decades in percentage River Water Quality in Hong Kong 2018 3 Figure 16 Water Quality Index gradings and E. coli levels in River Indus, River Beas and River Ganges Figure 17 Water Quality Index gradings and E. coli levels in Yuen Long Creek, Kam Tin River, Tin Shui Wai Nullah and Fairview Park Nullah Figure 18 Water Quality Index gradings and E. coli levels in Ha Pak Nai Stream, Tai Shui Hang Stream, Pak Nai Stream, Sheung Pak Nai Stream, Ngau Hom Sha Stream and Tsang Kok Stream Figure 19 Compliance with the Water Quality Objectives of the rivers in Lantau Island over the past three decades in percentage Figure 20 Water Quality Index gradings and E. coli levels in Mui Wo River Figure 21 Water Quality Index gradings and E. coli levels in Tung Chung River Figure 22 Compliance with the Water Quality Objectives of the rivers and streams in the Southwestern New Territories and Kowloon over the past three decades in percentage Figure 23 Water Quality Index gradings and E. coli levels in Tuen Mun River Figure 24 Water Quality Index gradings and E. coli levels in Pai Min Kok (Anglers’) Stream, Sam Dip Tam Stream and Kau Wa Keng Stream Figure 25 Water Quality Index gradings and E. coli levels in Kai Tak River List of Table Table 1 Stations with WQI gradings in 2018 changed as compared to 2017 List of Appendices Appendix A Summary of river water quality monitoring stations and sampling A-1 frequencies in 2018 Appendix B River water quality parameters and the methods of analysis B-1 Appendix C Key Water Quality Objectives (WQOs) for the river monitoring C-1 stations in the Eastern New Territories Key Water Quality Objectives (WQOs) for the river monitoring C-2 stations in the Northwestern New Territories Key Water Quality Objectives (WQOs) for the river monitoring C-3 stations on Lantau Island Key Water Quality Objectives (WQOs) for the river monitoring C-4 stations in the Southwestern New Territories and Kowloon Appendix D Water Control Zones in Hong Kong D-1 Appendix E Summary of water quality monitoring data for Shing Mun River E-1 (Shing Mun Main Channel and Siu Lek Yuen Nullah) in 2018 River Water Quality in Hong Kong 2018 4 Summary of water quality monitoring data for Shing Mun River (Fo E-2 Tan Nullah and Kwun Yam Shan Stream) in 2018 Summary of water quality monitoring data for Shing Mun River (Tai E-3 Wai Nullah and Tin Sum Nullah) in 2018 Summary of water quality monitoring data for Lam Tsuen River in E-4 2018 Summary of water quality monitoring data for Lam Tsuen River and E-6 Tai Po River in 2018 Summary of water quality monitoring data for Tai Po Kau Stream, E-7 Shan Liu Stream and Tung Tze Stream in 2018 Summary of water quality monitoring data for Ho Chung River in E-8 2018 Summary of water quality monitoring data for Sha Kok Mei Stream E-9 in 2018 Summary of water quality monitoring data for Tai Chung Hau Stream E-10 in 2018 Summary of water quality monitoring data for Tseng Lan Shue E-11 Stream in 2018 Summary of water quality monitoring data for River Indus in 2018 E-12 Summary of water quality monitoring data for River Beas in 2018 E-13 Summary of water quality monitoring data for River Ganges in 2018 E-14 Summary of water quality monitoring data for Yuen Long Creek in E-15 2018 Summary of water quality monitoring data for Kam Tin River in 2018 E-17 Summary of water quality monitoring data for Tin Shui Wai Nullah E-18 and Fairview Park Nullah in 2018 Summary of water quality monitoring data for Ha Pak Nai Stream, E-19 Pak Nai Stream and Sheung Pak Nai Stream in 2018 Summary of water quality monitoring data for Ngau Hom Sha E-20 Stream, Tai Shui Hang Stream and Tsang Kok Stream in 2018 Summary of water quality monitoring data for Mui Wo River in 2018 E-21 Summary of water quality monitoring data for Tung Chung River in E-23 2018 Summary of water quality monitoring data for Tuen Mun River in E-24 2018 Summary of water quality monitoring data for Pai Min Kok Stream E-26 and Kau Wa Keng Stream in 2018 Summary of water quality monitoring data for Sam Dip Tam Stream E-27 in 2018 Summary of water quality monitoring data for Kai Tak River in 2018 E-28 Appendix F Compliance with the river Water Quality Objectives in 2018 F-1 Appendix G Water Quality Index (WQI) for river waters of Hong Kong G-1 Appendix H Summary of river water quality improvements in 18 districts in 2018 H-1 River Water Quality in Hong Kong 2018 5 1. Introduction Rivers and streams in Hong Kong are generally short with small flows, many of which have their upstream sections located within the catchment areas of reservoirs where potable water is gathered. Other than for drinking water supply, the primary beneficial uses of the rivers and streams in Hong Kong include maintenance of aquatic life, as general amenity, flood prevention and storm water drainage. The main channel of Shing Mun River is the only watercourse used for secondary contact recreation activities. To provide data for water pollution control and management purposes, the Environmental Protection Department (EPD) has implemented a comprehensive river water quality monitoring programme since 1986. It mainly covers major rivers flowing through the urban areas, with one or more representative monitoring stations set up at the upstream and downstream sections of the main channels and tributaries. A number of small rivers and streams in the New Territories are also monitored. The monitoring programme serves the following purposes: evaluate the pollution status of river water; monitor long-term changes in water quality; provide a scientific basis for planning water pollution control strategies; assess compliance with the Water Quality Objectives (WQOs); and compile Water Quality Index (WQI). This report summarises the water quality of rivers and streams covered by EPD’s river monitoring programme in 2018.