Sentosa South Cove residents were greeted by the sight of their waterway turning pink since Tuesday afternoon, Jan. 12, causing alarm.

Prior to the change in colour, a foul smell resembling sewage emanated from the waterway a week ago, according to residents there.

The odour became more pronounced over the course of the week.

Residents also claimed that dead fish surfaced on the water between Jan. 6 to 10.

NEA still analysing data

The National Environment Agency (NEA) said they have collected several water samples from Sentosa South Cove since Jan. 9 and are analysing the results.

NEA added that there is no indication of any industrial or marine pollution.

No reports of dead fish at other public beaches in Singapore were made over the last weekend.

Management responds

Knight Frank Property Asset Management, in a Monday, Jan. 11 letter to Sentosa Cove residents sent a day before the waters turned pink, said no dead fish were found after the waterways were checked that morning.

The stench had also dissipated, KFPAM said.

But the contents of the letter proved premature, as the appearance of dead fish occurred on Tuesday, Jan. 12, just as the waters changed colour.

One resident said the colour of the water turned grey at one point on Wednesday.

The waters surrounding the North Cove remains unaffected.

But residents have been told to avoid water activities, SCRM said.

Possible algae bloom

The Straits Times reported that the cause of the pinkish hue in the water could be due to algae bloom.

A large amount of algae or microalgae accumulates in the water due to high amounts of phosphorus and nitrogen.

This could have been caused by the heavy rains in Singapore.

The algae that managed to thrive could have survived better in low light situations compared to other organisms, as Singapore was not as sunny.

The algae's pigment, which can be pink, brown, green and purple, turns the waters into a different colour.

The algae bloom then further removed oxygen from the waters, causing fish to die.

Top photos via Sentosa Cove residents