The Kaptai hydroelectric plant’s capacity to release water has drastically decreased, making it unable to keep saltwater from entering the Halda river upstream, which supplies water to Chattogram City.
The situation has forced Chattogram Water Supply and Sewerage Authority to suspend the operation of two water treatment plants based on the river during high tides, cutting water purification by roughly 50 million litres to 410-420 million litres.
Several city areas, such as Halishahar, Uttar Kattali, Patenga, Baklia, Lalkhan Bazar, Shulkabahor, Amanbazar, Ambagan, Shershah, Kalurghat Industrial Area, and Chandanpura, are experiencing water supply disruptions.
Chattogram WASA has 78,542 connections for residential customers and 7,767 for commercial clients.
Shafiqul Alam, a resident of Chandanpura, said the water in the area has been excessively salty for the past week, and the water supply is not as consistent as before. He expressed concerns that if this situation persists during Ramadan, the difficulties for residents will escalate.
“Last week, the water was dirty. The water is cleaner than before now, but we’re getting less water,” said Md Ajgar, a resident of Lalkhan Bazar.
Bappa Bhattacharya, a resident of Patharghata, said supply stops more often now. “And the water has become saltier.”
WASA deems the situation a “natural disaster” and says the crisis will not end without rainwater during monsoon.
Experts argue that continuously undertaking new projects without securing alternative reservoirs or water sources was a short-sighted approach. This could worsen the water crisis in the future.
DEPENDENCE ON KAPTAI WATER
The Kaptai power plant, constructed in 1962, is the sole hydroelectric project on the Karnaphuli River in the country, with a total generation capacity of 242 MW through five units. However, due to insufficient water upstream, only one unit is operational, generating 25 MW daily.
On Wednesday, the Karnaphuli hydroelectric power plant’s control room reported that the water level in Kaptai Lake was 76.86 Mean Sea Level or msl against its maximum capacity of 109 msl. Excess water is released through the dam when the water level surpasses the limit.
The plant’s Project Manager, ATM Abduz Zaher, said they have kept the only operating unit running to prevent any disruption to the supply to Chattogram WASA.
He said keeping the unit running would be impossible if the water level dropped below 70 msl.
If there is no rainfall by the end of this month, it is uncertain whether they will be able to continue operating the unit, he said.
As summer approaches, there is no assurance that the water level will increase in the upcoming months, as it all depends on natural rainfall, he added.
Water released from the Kaptai dam flows swiftly and blocks saltwater in the high tide via the Karnaphuli river from entering the Halda river. Water from Kaptai also enters the Halda river at normal times, reducing the salinity.
During the dry season, from November to March, if the Kaptai dam does not release enough water, the salinity level in the Halda river rises.
PRODUCTION DECREASES AT WASA PLANTS
The Mohara water treatment plant Phase-I draws 90 million litres daily within 500 metres of the Halda river’s confluence with the Karnaphuli. Similarly, the Sheikh Russel water treatment plant, located six kilometres upstream of the same confluence, requires 90 million litres daily.
According to Md Sadek Uddin Chowdhury, the executive engineer of the Mohara water treatment plant project, the salinity level of the water on Wednesday was 3,060 mg/litre, which was higher than 2,700 mg/litre on Tuesday.
He said they usually take water with a salinity level of 600 mg/litre for purification.
Last week, the salinity level in the Mohara section of the Halda river was recorded at 1,900 mg/litre.
“The treated water has a salt content of 350 mg/litre. However, we have stopped taking water from the river during high tide due to the current situation. Purification has to stop for about 10 out of 24 hours,” said Sadek.
He said the salinity level in the Madunaghat section of the river is somewhat less due to its distance from the estuary.
On Tuesday, the salt content per litre of water during high tide in Madunaghat was recorded at 1,800 mg/litre, up from 1,100 mg/litre a day before.
CHATTOGRAM WASA’S WATER TREATMENT CAPACITY
- Maximum 500 million litres per day.
- Four water treatment projects and 50 deep tube wells are involved in the process.
- Largest ones are Sheikh Hasina Water Treatment Plants- 1 and 2, located on the bank of the Karnaphuli river. These two plants purify around 280 million litres per day.
- Two other plants, Mohra and Sheikh Russel Water Treatment Plants, purify 180 million litres daily.
- From the deep tube wells, WASA can supply at least 40 million litres of purified water.
RAINWATER, WASA’S LAST RESORT?
The scarcity of purified water has somewhat rattled the Chattogram WASA.
The sole running water supplier of the port city expressed “regret” for the interruption of water supply in an advertisement published in a local daily on Wednesday, a day after the vice-president of the Chattogram metropolis unit of the ruling Awami League, Md Khorshed Alam Sujon, called on the managing director of Wasa to take immediate steps to resolve the scarcity.
In the advertisement, WASA authorities also requested the Chattogram City Corporation residents to be frugal about using water.
AKM Fazlullah, the managing director of Chattogram WASA, said that due to the lack of supply of water from Kaptai lake, water scarcity became serious in this dry season.
“Supply of purified water stood at 400-420 million a day due to the lack of water from Kaptai lake. That’s why we had to adopt rationing,” he said.
“Our hands are tied unless it starts raining regularly.”
Dr Md Idris Ali, a researcher of Karnaphuli river, was worried that the current water shortage would exponentially increase as soon as summer arrives.
“We are at the beginning of the spring season now. At least three more months of the dry season (according to the Bengali calendar) are ahead. Good rain is the only key here to resolve this crisis,” he said.
He said two gates of the dam are usually open during the dry season, but this time the water shortage has forced the authorities to open only one gate. “[WASA] should’ve coordinated with the power plant beforehand.”
“And the question arises whether the second water treatment plant on Halda was planned after analysis of data throughout the year from Kaptai dam and the lake. An alternative reservoir should’ve been planned for at least two to three months in the dry season.”
Idris suggested considering the increasing demand for water, global warming, lack of rainfall, the lake's depth and availability of water from the dam before taking up any project to ensure supply to the city.