On 24 July, the NSW Department of Climate Change, Energy, the Environment & Water (NSW DCEEW), were conducting microplastic testing on the Cooks River. Whilst conducting samples, a DCCEEW Marine Scientist noticed red discolouration in the water. Discolouration is one of many possible indicators of an algae bloom.

The DCCEEW Scientist sent the sample off to the lab for testing and confirmation. In the meantime, Water NSW notified the Canterbury Bankstown Council, Inner West Council & the Cooks River Alliance, advising “Very high levels of chlorophyll have been reported in a section of the river near Steel Park.”

The advice was to place temporary signage along the river, indicating that contact with the water should be avoided. The placement of temporary signage is part of the Water NSW Algae Bloom Response Management Guidelines. Accordingly, placed signage at several locations near the identified area. 

On 31 July, the results of the lab testing were received. The results confirmed that the dominant bloom species present in the samples from Cooks River are non-toxic. Present in the sample were two Dinoflagellates, Heteropcasa rotundata and a brown cryptomonad listed as Rhodomonas/Camplymonas sp, neither of which are harmful.

It should be noted that fishing within Cooks River catchment is by pole and line only and you should NOT keep your catch. Collecting or trapping shellfish is also illegal. 

Further Reading:

Guidelines to Management Response to harmful algae blooms, Water NSW

Cooks River Water Quality Report, NSW DCEEW

How WaterNSW manages algae blooms, WaterNSW

Fishing advice in Botany Bay & Cooks River, NSW Department of Primary Industries (Fisheries)