Hanoi filled in 17 lakes between 2010 and 2015, but did build seven new ones, according to an official report released in 2015.
Before the urban sprawl, a map shows Hanoi with a much larger water system. Photo courtesy of architect Truong Quy.
Last year, the Environment and Community Research Center in Hanoi studied 30 out of the 112 lakes in the city, and found 25 of them polluted due to uncontrolled waste and sewage.
Hoan Kiem Lake, the heart of the city, is the only lake untouched by urbanization. However, in February, officials said it is no longer capable of restoring itself and that oxygen levels are running low. Experts said fish and other creatures are slowly dying.
West Lake, the biggest lake in Hanoi, suffers from both invasive construction and pollution. From 1993 to 2001, its area fell from 526 hectares to 516 hectares.
In October 2016, over 200 tonnes of dead fish washed up in the lake. While authorities said a lack of oxygen might have killed the fish, the real culprit remains at large.
According to West Lake’s management board, it is estimated that 4,000 cubic meters of untreated wastewater is discharged into the lake everyday by households, restaurants and hotels.
Hoang Cau Lake, the biggest in Dong Da District, also witnessed thousands of dead fish floating to the surface in October last year. Experts said heavy rain following hot weather had polluted the air.
Giang Vo Lake is surrounded by several big hotels and many small businesses. Only cultivated fish and snails now live in the lake.
Dense housing and high buildings circle Ngoc Khanh Lake. In June 2015, months of purification caused green algae to grow, leaving a bad smell that made headlines.
On April 10, an investor proposed filling one hectare of Thanh Cong Lake for resettlement buildings.
Thu Le Lake, a part of Thu Le Zoo, has shrunk from 9,9 hectares in 2015 to 6,9 hectares in 2017.
Quang Ba Lake, a small lake to the northeast of West Lake, halved in size between 2010 and 2015.
Giang Huy - Hoang Phuong