Relevant units in Da Nang are taking drastic action to prevent unhealthy discharge into canals and lakes in order to control polution in these areas.

Picture was taken at the Thac Gian Lake on December 12. Photo: HOANG HIEP

Many fishes were suddenly found floating dead on Hoa Phu Lake and the drainage canal along Ha Hoi and Ngoc Hoi streets located in Hoa Minh Ward, Lien Chieu District, on November 29 and 30.

Mr Ha Van Thanh, the Director of the Da Nang Drainage and Wastewater Treatment Company said that the company has collected all dead fish floating on the above-mentioned lake and drainage canal, as well as used mineralization to remove odors from the water in these areas in order to improve the water environment.

Vice Chairman of Hoa Minh Ward People's Committee Pham Ngoc Lanh remarked that a patrol team has been set up to detect the unauthorized dumping of debris, garbage and other types of waste into the environment, especially at regulating lakes like Bau Sau Lake, canals near the Da Nang Oncology Hospital, along Tan Trao, Hong Thai, Nguyen Xi, Ngoc Hoi, and Ha Hoi streets, along the drainage canals.

According to the Environmental Protection Division of the Da Nang Department of Natural Resources and Environment, Lake E1 located in the residential area south of the Cam Le Bridge in Hoa Xuan Ward, Cam Le District showed serious pollution as the discharge of untreated domestic waste from nearby residential areas into the lake caused dead fish, and bad smell. Although the installation of aquatic rafts with a view to increase oxygen and the self-cleaning ability of the lake has been done, Lake E1 showed no significant improvement in its water quality.

Therefore, the Environmental Protection Division has proposed the municipal Department of Natural Resources and Environment to give high priority to installing  aerators at Lake E1 in efforts to increase dissolved oxygen in lake water. The focus is on selecting the best installation contractor, as well as developing  appropriate solutions for improving water quality of Lake E1.

According to the Environmental Protection Division, there are now 28 lakes across the city, of which, 18 are located in the inner city that are receiving untreated wastewater discharge from residential settings while 7 others still receive sewage leakage despite having a sluice system to separate domestic sewage. As a result, the nutrients and organic matter are found urban lakes, and microbial pollution of water often occurs.

There are seasonal changes in water quality of the city’s lakes. Especially, COD, ammonium, and phosphate concentrations in the lakes during the dry season are higher than in the rainy season. In particular, coliform and TSS concentrations in the lakes during the rainy season are higher than in the dry season.

The Environmental Protection Division has asked the municipal Department of Natural Resources and Environment to adopt effective solutions for a selected inner city lake on a trial basis with a focus on stopping illegal dumping and improving water quality of the lake.

Trial solutions include reducing the discharge of domestic wastewater and trash into lakes, collecting trash floating and found on the bottom of lakes, removing sediments and debris from the bottom of lakes, increasing dissolved oxygen in lakes, installing aquatic rafts to improve water quality, and maintaining the density of aquatic animals in the lake at an appropriate level. Heed will be paid to conducting  regular tests for water samples in the piloted lake for analysis and evaluation of the effectiveness of trial solutions in order to enable appropriate adjustments to solutions to be made in an attempt to ensure that the implementation is done in an efficient and economic way. These solutions will be adopted for other lakes across the city following the successful trials. 

Reporting by HOANG HIEP – Translating by H.L