Salinity increase in rivers forces WASA to curtail water supply by 50 million litres

The dry season has just begun, but excessive salinity has already infiltrated the water supply of Chattogram WASA, forcing it to halt production during high-tide and curtail supply by 50 million litres a day.

According to WASA, since late December, salt levels have been detected in the Karnaphuli and Halda rivers, with concentrations rising steadily through January and February. Now, in March, the salinity has reached an unbearable level, creating major concerns for the city's residents.

As of Sunday (2 March), the salinity level in WASA's water reached a record high of 2,320 mg per litre. Due to which, water production at four major WASA projects—Madunaghat Water Supply Project, Karnaphuli Water Supply Projects 1 and 2, and Mohra Water Supply Project—has been halted for several hours daily. This has resulted in a reduction of at least 50 million litres of water per day, leading to significant supply disruptions.

Chief Engineer of Chattogram WASA Maksud Alam confirmed the severity of the situation, stating that the reduced discharge from Kaptai Lake has resulted in excessive salinity in the Karnaphuli and Halda rivers. 

"On 2 March, a maximum of 2,320 mg of salt per litre was recorded in the water. Due to this, WASA is forced to halt water production during high tide, reducing daily output by 50 million litres", he added.

For the past few years, high salinity levels have been a recurring issue in WASA's water supply. The problem has worsened due to reduced water discharge from Kaptai Lake, a key freshwater source. Currently, four out of five units at the Kaptai hydropower plant are non-operational, significantly lowering water flow downstream. This has allowed salty seawater from the Bay of Bengal to push inland through the Karnaphuli River and enter the Halda River. As a result, WASA's overall water production capacity has declined.

The Madunaghat project, which previously produced 90 million litres of water daily, is now producing only 75 million litres. The Karnaphuli projects have seen a reduction from 280 million litres to 260 million litres, while the Mohra project has dropped from 90 million litres to 70 million litres per day. Experts warn that if there is no rainfall soon, the situation could worsen further in the coming days.

The crisis has also impacted electricity generation at Kaptai Hydroelectric Power Plant, the country's only hydropower facility. The lake's current water level stands at 89.39 MSL (Mean Sea Level), significantly lower than the standard 93.60 MSL. Due to the water shortage, only one of the five units is currently operational, generating a mere 40 MW of electricity instead of the plant's full capacity of 242 MW.

To address the crisis, WASA is actively considering alternative solutions to ensure a stable water supply. However, without rainfall or an increase in freshwater flow from Kaptai Lake, the crisis is expected to intensify.