Brazil: Lake In Sao Paulo Turns Bright Green, Visitors Shocked With Transformation

Its verdant colour stems from a combination of an algal bloom, abundant nutrients, high temperatures and a lack of rain in the Brazilian metropolis, City Hall said in a statement Thursday. It added that the lake's low water level makes it harder for a pump to remove the algae.

Sidney Cardoso, a 49-year-old photographer, said he had never seen the lake's water look so green.

“We know that it's different when it's totally full,” he said.

Considered Sao Paulo's biggest park, Ibirapuera lies close to the city's centre. It is home to the Afro Brazil Museum and the pavilion that hosts the Sao Paulo Art Biennial. The lake has been called “the park's soul”. Many paulistanos, as Sao Paulo's residents are known, like to exercise near it each day, and thousands of families come on weekends for picnics and to play sports in the area.

The lake's green hue is only the latest reflection of dire climate conditions. Earlier this month, drought turned Sao Paulo's Pinheiros River green, also due to an algae bloom. And the city's skies became gray, filled with smoke from distant fires in the Amazon rainforest.

Beside the lake on Thursday, Silvia Alves, a nutritionist who often exercises there, said she felt that the algae had improved the area's air quality.

“As I breathe, I get more euphoric than usual,” she said after a set of jumping jacks.