Blue green algae detection in Grahamstown Dam

HUNTER Water maintains that local drinking water remains safe to drink, and “robust treatment processes continue to be effective”, following a high detection of blue green algae in a sample collected from Grahamstown Dam.

The sample was collected from raw untreated water in the middle of Grahamstown Dam and contained high numbers of cyanobacteria (Microcystis), also known as blue green algae.

“Concentrations were much lower in samples collected on the same day from the northern and southern ends of the dam, including near the offtake to our water treatment plant,” Hunter Water said in a statement.

The sample collected in the raw untreated water at Grahamstown Water Treatment Plant (WTP) also showed low levels.

Hunter Water stated that the Grahamstown water supply scheme has robust monitoring and treatment processes in place for detecting and removing blue green algae and the current bloom “does not pose a risk to our region’s treated drinking water”.

“We manage our water supply through a multi-barrier catchment-to-tap process, ensuring that our drinking water is safe, reliable and high quality at all times,” Hunter Water said in a statement.

“Blue-green algae are a natural component of waterbodies like Grahamstown Dam and play a crucial role in the ecosystem by producing oxygen through photosynthesis.

“When conditions are favourable, such as high nutrient levels – following rainfall and runoff – and warm temperatures, cyanobacteria can form blooms, which can lead to a reduction in water quality and can pose risks to humans, pets and livestock if they drink the untreated water.”