That hydropower plants in the Vu Gia - Thu Bon river basin have discharged water at the minimum level or stopped operating over the past 9-12 days has made the river water level very low and significantly increased the salinity levels at the Cau Do (Red Bridge) Water Supply Plant's raw water intake gates.

In recent days, relevant departments and agencies across Da Nang have been making every effort to take measures to solve salt-water contamination and ensure sufficient water for residents' daily lives.

A temporary water dam has been built on Quang Hue River, making the Vu Gia River's water source still flow to the Thu Bon River even when the Vu Gia river's water level drops to 1.8m on the morning of May 1. This affected the raw water source at the An Trach pumping station. Photo: H.H

High level of salinity

Following recent direction made by Quang Nam Province government, some hydropower plants on Vu Gia - Thu Bon river basin have stopped discharging water into the lower sections in order to gradually bring their water level to the level in accordance with the regulations of the inter-reservoir operation process in Vu Gia - Thu Bon river basin.

In particular, the Song Bung 2 hydropower plant has been suspending operations from April 28 until May 10, whilst the A Vuong hydropower plant has been shut down on April 28 and 29, and from May 3 - 10.

Given the fact that hydropower plants discharge water with minimal flow or stop operating has caused salinity at the Cau Do (Red Bridge) Water Supply Plant's raw water intake gates to increase rapidly with above 500mg/l since April 29.

The highest salinity level recorded at the Cau Do (Red Bridge) Water Supply Plant’s raw water intake at dawn on April 30 was 2,485mg/l, around 8.2 times higher than the allowed limits.

The Da Nang Water Supply JSC (DAWACO) alternately operates anti-salinity pumping stations, and old and new water transmission pipeline with a maximum capacity of 210,000m³/day in order to bring fresh water from the Yen River at the upstream of the An Trach weir to the Cau Do and Airport water plant for production, as well as collect water from Cam Le River to ensure domestic water supply for the city.

In addition, DAWACO has advised customers to take proactive measures to store water during off-peak hours, and have a plan to use water economically and reasonably.

DAWACO General Director Ho Minh Nam said that during the holidays for April 30 and May 1, the highest water supply capacity for the whole city was 334,443 m³/day and there was no water shortage.

Continue to effectively operate anti-salinity pumping stations

During the holidays, when the A Vuong hydropower plant stopped operating on April 28 and 29, the water level of the Yen River at the upstream of the An Trach dam dropped to the lowest level of 1.77m in the early morning of May 1. Therefore, DAWACO could only operate 4 out of the 11 pumps of two anti-salinity pumping stations to provide fresh water for residents' daily lives, and agriculture and industrial production in the city.

At present, the A Vuong hydropower plant is continuing to stop operating from May 3 - 10, making the city's domestic water supply at risk of unsafel. The main reasons are thought to be that the water level of the rivers is lowering, salinity level increases due to tide, and demand for water continues to increase as factories return to production.

In order to proactively respond to saltwater intrusion and supply enough water for the city, DAWACO continues to strengthen monitoring of source water quality and safety for the operation of water plants, and prepare facilities necessary for safe water supply.

In the coming days, the municipal Department of Construction continues to ask DAWACO to regularly monitor closely the situation of salinisation at the Cau Do (Red Bridge) Water Supply Plant's raw water intake gates as well as the water level at the An Trach weir to operate at maximum capacity of the existing anti-salinity pumping stations in case the Cam Le River has severely affected by the intrusion of saline water.

During the operation, if there is a risk of water shortage, DAWACO urgently reports to the municipal Department of Construction to promptly advise appropriate plans, absolutely not to be passive in the implementation of water supply solutions for the whole city.

Reporting by HOANG HIEP - Translating by M.DUNG