On Monday afternoon, thousands of dead fish washed up along the edge of West Lake, as the city’s largest freshwater body, and an overpowering stench assailed the nostrils of local residents.

A carp weighing more than 2kg floating on the surface of the lake is brought ashore.

Around 3 p.m., sanitation workers collected trash and picked up the dead fish.

Perch, carp and other fish joined plastic and other trash on the lake edge.

A dead tortoise washed ashore near the statue of two dragons on the West Lake.

Strangely, fishing enthusiasts dangled their lines even as dead fish stank up Nhat Chieu Street.

A senior official from Hanoi’s transport department has blamed the fish deaths on the sudden shift in the weather. However, no official conclusion has been reached.

The West Lake’s management board estimates that 4,000 cubic meters of untreated wastewater is discharged into the lake every day by households, restaurants and hotels on the banks.Dead fish alongside coconuts thrown from nearby cafés. Residents and passers-by have complained about the foul smell.

A local man caught a big fish from the West Lake, but did not dare take it home.

Hanoi has become notorious for its foul water in recent years. In 2016, fish dying en masse in the capital city’s West Lake, estimated at around 200 tons, shocked the country. This was followed by fish dying in the Linh Dam, Van Quan, Ngoc Khanh and Hoang Cau lakes.

Hanoi has over 100 ponds and lakes scattered across the city, but many of them are polluted by sewage and rubbish.

The city hopes to mitigate the problem with a $726 million sewage treatment plant, work on which began in October 2016 and is scheduled to finish in three years. The system will treat 270,000 cubic meters of sewage collected from the Lu, To Lich and Nhue rivers everyday.