PETALING JAYA - Of the 477 rivers monitored by the Department of Environment last year, 168 were slightly polluted while 33 were polluted, Datuk Seri Dr Wan Junaidi Tuanku Jaafar said.
The number of clean rivers, however, has increased from 244 in 2014 to 276 last year. Water quality was assessed from a total of 5,469 samples taken nationwide.
The main reasons for the pollution was high levels of bio-chemical oxygen demand, ammoniacal nitrogen and suspended solids due to inadequate treatment of sewage and effluents from agro-based and manufacturing industries, animal farming, domestic waste and improper earthworks and land clearing activities, the Natural Resources and Environment Minister said.
"Why polluted? Because of domestic and industrial waste, and buffer zones between development areas and rivers that aren't big enough.
"Siltation goes into the river and reduces river capacity and quality. Once water quality is bad, even the machine used to purify and make it drinkable, will stop functioning. Some rivers are reaching that level," Dr Wan Junaidi said in an interview.
It would be alarming if the main rivers that supply raw water for public consumption was polluted, he said, adding that the Total Maximum Daily Load (TMDL) - a new mechanism used in developed nations - would be implemented this year to assess the permissible pollution load of rivers.
Research has been done locally on the mechanism that sets the maximum amount of a pollutant which a body of water can receive while still meeting water quality standards, but operating it full-scale hasn't been worked out yet, he said.
Under the current assessment method, the pollution level was based on the concentration of pollutants.
TMDL, which will complement the existing assessment method, was the best way of controlling pollution because the carrying capacity of each river could be identified and enforced, he said.
"The pilot project findings will be presented to the respective state governments for legislation and enactment.
"It's the states that will determine TMDL's effectiveness," he said, adding that RM50mil was approved under the 11th Malaysia Plan for the integrated management of 25 main river basins, each measuring over 8,000ha, nationwide.
The move, he said, would improve water quality, reduce flood risks, ensure water supply and protect the environment.
On April 3, Sunday Star reported that despite having four times more than what we need, dry taps were part of life here.
The main reason, according to Institution of Engineers Malaysia president Datuk Lim Chow Hock was pollution.