What’s that oily-looking substance on Belongil Creek?
What looks like an oil slick on the surface of Belongil Creek has been confirmed to be marine blue green algae, according to Byron Shire Council.
The council's staff have investigated the slick this week and took samples.
Those samples were sent off or testing and returned a positive result for trichodesmium.
The council's biodiversity and sustainability co-ordinator, Chloe Dowsett, said this is a natural event and one which is important to the marine environment.
"Marine blue green algae is naturally-occurring and travels down the coast with the East Australian Current during the summer months," Ms Dowsett said.
"It sometimes gets trapped in our coastal creeks and because of its appearance people often think it is an oil spill or something toxic.
"This algae is often slimy and smells and can vary in colour from red, brown, green or cream."
Avoid swimming in the water and do not eat shellfish from areas affected by the algae.