The Sungai Selangor dam and Klang Gates dam – each have roughly just over two months of water supply before they hit the critical stage.
During the country’s worst recorded water crisis in 1998, 4.2 million people had to survive on 2,553 million litres per day (MLD), a shortage of 105 MLD.
This time round, 7.1 million people need 4,900 MLD but only 4,367 MLD is available – a shortage of 533 MLD.
The only solution is for the dams to get, by April 30, rain equivalent to the average monthly rainfall for November – one of the wettest months of the year.
Selangor Water Management Authority (Luas) director Md Khairi Selamat said water at the Sungai Selangor dam might last 71 days while water at Klang Gates dam 88 days.
“This is assuming the output remains as it is right now, which is 1,000 MLD for Sungai Selangor and 100 MLD for Klang Gates.
“Also, we need 200mm of rainfall for the Sungai Selangor dam to rise to 55% from its current level of 37.38%. Until we reach that target, water rationing needs to continue,” he told a press conference yesterday.
In 1998, 1.8 million people in Selangor and Kuala Lumpur were affected by a six-month long water rationing exercise – from March to September – because of the El Nino phenomenon.
The long drought and absence of rainfall that year led to almost critical water levels in four dams – Batu, Klang Gates, Langat and Semenyih.
A water rationing exercise that started on April 20, 1998, ended on Sept 16.
This year, Selangor began water rationing in early March, with the fourth phase expected to end on April 30.
Sungai Selangor dam’s critical capacity is 69 million cubic metres (Mm3) and the Klang Gates dam 4.7Mm3.
Of the seven dams in Selangor, four are below the safe level of 70%, including the Sungai Selangor and Klang Gates dams.
Currently, the Klang Gates dam is at 53.89% capacity, Langat dam 49.47% capacity and Sungai Tinggi dam 61.29%.
Md Khairi said the state was banking on increased rainfall next month, when the wet monsoon kicks in, to help raise the dams’ capacities and see it through even more difficult times expected between June and October.
“Cloud seeding operations will also continue next week and will be more focused on the water retention areas of Sungai Selangor and Klang Gates dams until May 31, subject to weather conditions,” he said.
Khairi said Syabas’ announcement to relax water rationing came about after the treatment plants in Batu 11, Cheras and Bukit Tampoi were reopened on March 30.
“The plants, which were previously closed following high ammonia levels in the rivers, could be reopened as recent rains diluted the ammonia content in the rivers. This will allow for more treated water production, so the relaxation of water rationing can happen,” he said.
In Shah Alam, Selangor Mentri Besar Tan Sri Khalid Ibrahim defended the rationing exercise, saying that the two days on and two days off rationing was the best method.
He said the decision was decided by a group of experts from the water industry.
“The rationing exercise has, in fact, ease the water problems currently faced in districts and areas that have not received water supply for weeks earlier,” he told the state assembly yesterday.