BENGALURU, India (AP) — Sunil Kumar rowed his small boat, moving a few feet at a time, while he spread a fishing net across the weeds floating like a green carpet on Doddajala Lake. The ends of the net were then carried ashore and tied to a tractor and an earthmover, which pulled the bundled plants toward laborers ready to drag them out with pitchforks.

Once each netful of weeds was scooped out, they repeated the process. Kumar, a fisherman who grew up nearby, and the others have been working 10 hours a day for two weeks to clean this water as part of a wider effort to restore polluted lakes that are in danger of disappearing around Bengaluru, India’s fast-growing tech hub.

“Once the weed grows, all fish die. This is because the weed cuts out oxygen flow below the water and, of course, nothing can survive in the water after that,” he said.

City authorities and volunteers have cleaned and restored dozens of lakes in recent years, but much work remains. Bengaluru had more than 250 lakes in the 1970s. Today, roughly 180 remain and many are in a poor state. Water experts said the city’s explosive growth and mismanagement of sewage have severely damaged a centuries-old network of cascading lakes that sustained communities in this otherwise dry plateau.

Doddajala Lake, a 94-acre (38 hectares) body of water, sits along the city’s northern outskirts near its airport in an area where multistory residential buildings, resorts and offices are interspersed with older mud-tiled houses and farmland. R. Byregowda, the head of the nearby Doddajala village, attributed the growth to the area’s proximity to the airport.

“You can’t imagine the kind of changes in my village in just the last five years,” said Byregowda, who’s been helping with the lake cleanup effort.

The lake cleaning is a joint effort by citizen groups focused on weed removal and local government officials who built a walking path with benches and planted trees with help from private donors.

Kumar, who has helped clean four other lakes, said rampant growth of weeds fed by nitrogen and phosphorous from sewage can be disastrous for the lake and its fish. Entangled in the weeds and on lake shores, the volunteers also encounter plastic bottles, clothes and other garbage.

“When I was a child, the water in the lake was clean and we used to swim in it, but now it’s mixed with sewage water,” Kumar said.

Lakes dwindle in a city once known for them

The lakes’ health can have wide-ranging implications for a region facing weather extremes amid a warming climate. Experts and advocates say long-term planning is needed to ensure the lakes can defend against flooding by collecting excess rainwater and bolster the city’s water supply by gradually releasing their contents into groundwater sources. The lakes can also keep surrounding areas cooler in the summer.

“Lakes can act as cooling zones during extreme heat events, and they can act as a flood buffer when there are extreme rainfall events,” said Shashank Palur, a Bengaluru-based hydrologist with the think tank Water, Environment, Land and Livelihood Labs.

The series of lakes and reservoirs were developed in the 16th century to support fishing, agriculture and domestic use in an otherwise dry region. The cascading system connected by water channels and stormwater drains conformed to natural valleys. Palur noted that the city has no major river running through its boundaries to feed it.

As the region urbanized in recent decades, many rain-fed lakes, which were dry in the summer months, were built over. Meanwhile, poorly built or maintained sewage pipes or new buildings without proper connections caused leaks that resulted in sewage water being swept into stormwater drains. When this reaches the lakes, it spurs algal blooms and invasive weeds.

A 2017 study by the Bengaluru-based Indian Institute of Science, the latest such data available, found that 85% of Bengaluru’s water bodies are polluted.

Palur said city officials are often playing “catch-up” as newer homes and offices are occupied before sewer connections are installed, resulting in sewage being stored locally and then illegally dumped into lakes or stormwater drains.

“Sewer connections and water supply connections haven’t reached the entire city. So, lakes become polluted,” he said.

Volunteers lead lake restoration efforts

Volunteer groups have restored dozens of lakes, sometimes with help from city officials. The revival of suburban Jakkur lake, led by volunteers, received a national award in 2019.

“Wherever a lake has been saved in Bengaluru, it will be because a citizen group has fought for it,” said V. Ramprasad, co-founder of the volunteer group Friends of Lakes that has helped rejuvenate more than 20 water bodies. “We are the eyes and ears of that area.”

A 2012 court verdict had mandated government officials to lead lake restorations, but the ruling has been poorly implemented amid confusion from state agencies, said Bhargavi Rao, a researcher and environmental activist.

“Given that we live in a society that is already divided by caste, class, religion, language, various other identities, it is very important that these public commons are maintained by the local governments,” she said.

While the volunteer work has been important, advocates say government leadership is needed to ensure the lakes’ long-term survival. Rao said individual efforts are well-meaning but might not be long-lasting.

Ramprasad said that it’s important that restoration efforts go beyond cleanup and beautification. The efforts should prioritize harvesting rainwater to defend against floods and restore groundwater, aims that can require more resources and planning.

City officials said protecting lakes is a top priority, especially after a severe shortage of drinking water in 2024. Authorities said lakes can help replenish groundwater, allowing more water to be extracted during hot summer months.

“Conservation of these lakes is critical for the water needs of Bengaluru city, both underground water as well as for the ecosystem around the lakes,” said Ramprasath Manohar, chief of Bangalore Water Supply and Sewerage Board.

Manohar said the state government has installed fences around 160 lakes and removed encroachments, among other steps.

Kumar, the fisherman helping with cleanup, said lakes can also help residents cope with heat.

“People sit in cars and switch on their AC nowadays, but then when you sit here by the lake, you don’t require any AC. It is so cool here,” he said.

Kumar said he’s happy to work as hard as needed to clean the lake.

“Once it’s fully clean, I can also get back to fishing here and more people will come to enjoy the lake,” he said.

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