Hanoi (VNA) - The water quality in Hanoi’s lakes, including 86 in the innercity and 44 on the outskirts, earmarked for renovation has improved markedlyafter months of dredging and cleaning, experts have announced.

Lakes such as Ngoc Khanh, Kim Lien, Ba Mau and Thien Quang were once severelycontaminated and needed urgent cleaning to protect their bio-systems, safetylevels and the surrounding areas.

"I’ve seen a big improvement. The water in the lake [Ngoc Khanh Lake] iscleaner and less smelly," said Vu Khac Hoa, a resident of Hanoi’s Ba Dinhdistrict, who lives near Ngoc Khanh Lake.

The surrounding area had also been beautified, he said.

“The investor has separated the water drainage system so the waste water fromresidential areas no longer flows into the lake,” Van Dinh Hung, anotherresident told Vietnam Television.

Bui Ngoc Uyen, from the Hanoi Sewage and Drainage Company, which is responsiblefor maintaining Hanoi’s lakes, said over the past year the company has usedchemical products together with a number of measures like the installation ofaquatic rafts with a view to increase oxygen and the self-cleaning ability ofthe lakes.

The main task for Hanoi lakes is to regulate drainage, drought andenvironmental landscapes and they have met these criteria, experts say.

According to the Centre for Environment and Community Research (CECR) reportreleased in 2015, the number of lakes in Hanoi decreased to 112 from 122between 2010 and 2015. The water surface also dropped by72,000sq.m compared to2010.

Data from the CECR analysis showed that a lot of lakes, which were oncebeautiful spots for the city’s residents to visit and enjoy, were seriouslydeteriorating due to rising levels of pollution.

Test on water samples taken at these lakes revealed that lakes contained anexcessive amount of pollution, compared to national standards.

To improve the water environment at lakes, the municipal People’s Committee hadassigned the Department of Natural Resources and Environment to research andimplement the testing and treatment of water pollution in rivers and lakes inthe city.


The experiment was conducted in 12 lakes including Ngoc Khanh, Xa Dan, Hai BaTrung, Kim Lien, Ngoc Ha, Den Lu, Van Quan and Giang Vo. In addition, theDepartment handled the pollution of water in Ho Tay (near the Water Park) andMy Dinh ditch.

In 2016, the municipal People’s Committee has directed the Hanoi Sewage andDrainage Company to implement the treatment of Redoxy-3C technology for 83lakes in the city to enhance the water quality.

After the product was proved effective during trials in Ho Me, Ba Mau and GiapBat Lakes, Redoxy-3C has been applied to other lakes in the city includingHoan Kiem Lake (Sword Lake).

Covering an area of around 12 hectares, the lake is located in the historicalcentre of the city. Not only important historically, Hoan Kiem Lake has abeautiful landscape, and is considered a scenic, relaxing escape from the chaosof the Old Quarter.

However, the lake is severely polluted and has lost the ability to reviveitself. Its water quality is getting worse by the day, its pH level is high,and the amount of suspended deposits is higher than the permissible limit atall five monitoring locations, according to the Hanoi Sewage and DrainageCompany.

The lake also has high organic contamination, with the indices for bothbiochemical oxygen demand (BOD) and chemical oxygen demand (COD) two times overthe limit.

The lake water has lost its distinctive dark green colour in several spots, andthere is a one-metre layer of mud at the bottom of the lake, causing pollutionand reducing the water level by 0.5 to 0.8m.

By the end of last year, the company was assigned to dredge and clean Hoan KiemLake.

After over one month of cleaning, the original colour of water in the lake hasreturned and there is no longer a bad smell.

Pham Tung Lam, head of the Management Board of Hoan Kiem Lake, said the pollutedmud layer disappeared when the dredging process had finished.

“It would be a good opportunity for creatures to develop in the lake,” he saidadding that as a matter of fact, a tortoise had been seen laying eggs near NgocSon temple.-VNA