Members of the public are being asked to avoid contact with the Kingswell Creek, as compliance staff investigate an unknown discharge into the water.
Compliance manager Simon Mapp said staff were notified about an oil substance on the surface of the creek at the beginning of this week. Early investigations found the film on top of the water was consistent with a natural process that occurs when plant material breaks down.
Further investigations indicated there was a more serious issue contributing to the condition of the creek and staff yesterday located a possible discharge point. The discharge is believed to be coming from a private property although the specific source of that discharge point, which is underground and unmapped, has not yet been identified. The exact contents of the discharge are also unclear, although it does not appear to be oil.
Tests carried out have identified very low oxygen levels in the water, along with high ammonia nitrogen levels at several points in the creek, from Seaward Bush through the length of the creek.
"Initial tests have shown very low dissolved oxygen and we have noted a number of dead eels in and around the creek.
"The lack of rain recently also means the creek is very low, particularly at the Rockdale Road end and, with little rain expected in the next few days, there is unlikely to be any significant improvement in the short term."
Signs have been put in place advising people to stay out of the water and an investigation into the source is ongoing.