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Sampling Programme on the Impact of Livestock Activities on Watercourses in the North and Yuen Long Districts
To address the impact of livestock farming activities on watercourses, i.e., the seriousness of non-compliance with the Waste Disposal Ordinance when the livestock farmers discharged their livestock trade effluent to watercourses, EPD started in late 2004 a monitoring programme to assess the conditions of watercourses in the North and Yuen Long Districts. About 50 sampling points were set up in those watercourses which received, among others, discharges from major livestock farm clusters. For comparison purpose, another 27 sampling points were set up in those watercourses which received no livestock discharge (i.e., at upstream of the livestock farms). Inspections will be conducted on a seasonal basis and during the inspections, photos will be taken to record the conditions of the watercourses and, water samples will be collected for chemical analyses in the laboratory.
Two water quality parameters: 5-day Biochemical Oxygen Demand (BOD) and Suspended Solids (SS) levels were selected for the chemical analyses, as these two parameters are also stipulated on the Waste Disposal (Livestock Waste) Regulations for effluent discharged from livestock farms. Under the Regulations, both the BOD and SS levels in any discharge from livestock farms shall not exceed 50 mg/L. In short, if the discharges complied with the Regulations, the BOD and SS levels in the watercourses would not exceed 50 mg/L.
Conditions of the watercourses and our enforcement priority on follow-up actions to assess the compliance of the livestock farms can be divided into three categories, based on the water quality results.
| BOD and /or SS levels |
Watercourse condition |
Enforcement priority |
| <50 mg/L |
Acceptable |
Low |
| >50 - 500 mg/L |
Unacceptable |
Medium |
| >500 mg/L |
Highly unacceptable |
High |
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Our following up actions will include an inventory check on the dischargers, followed by field inspections to trace and identify the polluters. Should sign of illegal discharge be noted in the farm vicinity, liaisons with the livestock farm owners and inspections to their wastewater treatment facilities to identify the problems and, solicit their support to rectify and improve the situations would be arranged. Where applicable, warning letters, followed by a Statutory Notice demanding for the farm owner's immediate action(s), would be issued if the pollution problems were mainly due to improper operation / inadequate maintenance of the treatment facilities. Enforcement actions, including ambush operations, will be arranged or stepped up as appropriate and prosecution will be initiated to catch illegal discharge red-handed accordingly.
Summary of the surveys
Below is a chart showing the conditions of watercourses at downstream of major livestock farm clusters in the North, Yuen Long (East) and Yuen Long (West) Districts, based on the water quality data collected during the surveys.
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