River Water Quality Monitoring Programme

The EQMP River Water Quality Monitoring Network

The monitoring of the nation’s major river basins in the EQMP comprises:

  • 30 Continuous River Water Quality Monitoring Stations (CRWQM)
  • 1353 Manual River Water Quality Monitoring Stations (MRWQM)
  •  4 Rapid Response Teams (RRT) to be deployed to undertake investigative sampling or special study

The CRWQM network provides continuous river water quality data which is transmitted to the Environmental Data Centre (EDC) on a scheduled basis. The network comprises monitoring stations that are located upstream of intake points in major river systems in Malaysia with the exception of the station located at Sg Klang which is aimed at providing fata to assess the effectiveness of the River of Life project

The river water quality parameters measured at the CRWQM stations are generally considered as the key parameters related to the assessment of river water quality and includes parameters that allow for the generation of the Water Quality Index (WQI)

Instrument For River Water Quality Monitoring


EXO2 multiparameter sonde for :-

  • Temperature
  • Potential of Hydrogen (pH)
  • Barometric Pressure
  • Oxidation Reduction Potential (ORP)
  • Conductivity
  • Total Dissolved Solids (TDS)
  • Salinity (derived from conductivity and temperature)
  • Rugged Dissolved Oxygen (RDO)
  • Turbidity
  • Total Suspended Solids (TSS) (derived from turbidity)

BlueBox control system for :-

  • Chemical Oxygen Demand (COD)
  • Biochemical Oxygen Demand (BOD)
  • Total Organic Carbon (TOC)
  • TSS
  • Nitrate

Sontek  side-looking acoustic flow meter for :-
  • Flow
  • Discharge
  • Water Level
  • Temperature

Data from the CRWQM network is used to assess the raw water quality before it reaches the water treatment plant. Hence, a target of Class II, consistent with raw water quality suitable for conventional treatment, is the desirable water quality. Pre- determined alert levels allow for the timely recognition of potential pollution event that may compromise the treatment capability of the downstream treatment plant.

In addition to the appropriate mitigating measures that are activated at the treatment plant, such alerts also prompt the DoE, supported by PSTW field staff to identify the source of the pollution so that appropriate actions can be taken. To facilitate this crucial task, a comprehensive source inventory has been developed for each of the 30 CRWQM station.

The MRWQM network numbering 1353 monitoring stations located at major rivers, allows for the comprehensive assessment of the nation’s river water quality.  Each of the station is monitored 6 times a year, encompassing both high and low flow regimes. At each station, in situ measurements are taken and water samples collected, preserved in the appropriate manner and sent to the Contact Laboratory to be analysed. In total, 34 water quality parameters are measured, comprising WQI parameters, heavy metals, organic and inorganic chemicals as well as microbes. The number of water quality parameters are doubled every three years to provide an even more comprehensive database.

In addition to conducting the monitoring works at the designated MRWQM stations, our team of field technicians are also tasked to recognise pollution incidents based on clearly defined indicator observations well as in situ measurements. When such events are recorded, a Notification of Pollution Event (NPE) is reported to the DoE for further investigation and subsequent follow-up action.

The RRT, equipped with all the river water quality monitoring paraphernalia, including the ability to deploy continuous monitoring systems are brought into action upon instruction by the DoE. Such instructions are prompted by the reports of pollution incidents. In addition, the RRT may also be deployed to undertake special studies usually associated with water pollution.

As with other scopes of works in the EQMP, the RRT adheres to a clearly defined SOP that also require close collaboration with State DoE officers and other relevant agencies. The ultimate goal of the team is to generate sufficient and appropriate data to allow for

i) the identification of the cause or source of the incident,
ii) the identification of the nature, temporal and spatial extent of the impact of the incident
iii) recommendations of mitigating and preventive measures.