Environmentalists highlight declining water quality in Bali's lakes

Denpasar (ANTARA) - Environmentalist and academic from Udayana University, Professor Ni Luh Kartini, has highlighted the declining water quality in Bali’s lakes, attributing it to pollution, sedimentation, and human activities in the surrounding areas.

In Denpasar, on Friday, Professor Kartini stated that most of Bali’s lakes, located in agricultural areas, are facing serious threats due to the use of pesticides, chemical fertilisers, domestic waste, and land erosion.

These conditions cause the lake waters to become increasingly fertile, leading to eutrophication, which impacts the decline in oxygen levels in the water.

“Currently, the water in Lake Batur is starting to turn green. This indicates that the oxygen content is decreasing and causing fish mortality,” she said.

The four major lakes in Bali are Lake Beratan, Lake Tamblingan, Lake Batur, and Lake Buyan.

In addition to pollution, sedimentation is also a major problem causing the lakes to become shallower.

Professor Kartini revealed that the depth of several lakes in Bali has decreased significantly compared to their previous condition.

“Lake Buyan, which used to have a depth of around 140 meters, now has a depth of only about 80 meters. Similarly, Lake Batur, which previously had a depth of 120 meters, now ranges from 64 to 80 meters,” she said.

She added that the sedimentation also has an impact on the declining discharge of springs, which have been a source of water for the community.

Furthermore, the presence of floating net cages and invasive red devil fish in Lake Batur is also a serious concern. Professor Kartini stated that the population of red devil fish now dominates up to 60 percent and threatens the existence of native endemic fish.

“Red devil fish can live in low oxygen conditions, so they reproduce very quickly and consume native fish,” she said.

To restore the lake ecosystem, Professor Kartini emphasised the importance of implementing an organic farming system in the areas around the lakes, integrated management of domestic waste and garbage, and supervision of development in the lake buffer zones.

She also believes that the government has shown seriousness in addressing environmental issues through the formation of a working group to accelerate waste and environmental management. However, she believes that these efforts still require intensive assistance to the community.

“This environmental issue is closely related to the development of character and community awareness, so it cannot only rely on regulations,” she said.

Professor Kartini affirmed that law enforcement against violations in the lake buffer zones must also be carried out consistently through the application of rewards and punishments.

Currently, the community in the Lake Batur area is also starting to move through the formation of a lake conservation forum involving surrounding villages to formulate concrete steps to protect the lake ecosystem sustainably.

“Lake conservation cannot be done alone. There must be communication, coordination, and collaboration from all parties,” she said.