Timbara Creek, Surfside given the all clear by EPA
Timbara Creek, Surfside and its outfall to the Clyde River have been given the all clear by EPA inspectors who were called to the location following the sighting of dead fish in the presence of a strong sewer smell. A concerned local contacted the EPA in Queanbeyan who in turn contacted an Environmental officer from Council to inspect the sight as there were fears that the creek had flooded into the sewer pump station and caused the fish kill. With the very strong smell of "sewer" the resident feared for the Clyde River being impacted. Matthew Rizzuto, Head of Queanbeyan Operations – South East Region advised today "Natural waters adjacent to urban development will nearly always contain some sort of bacteria following a storm event. It is for this reason that oyster growing areas are closed for harvesting following storm events. As a result of the recent rainfall in the Batemans Bay area, the Clyde River oyster growing area has been closed since the 4th of March" Tests have now come back giving the creek the all clear of any sewer contamination. In his report Matthew Rizzuto writes: "On this occasion, the EPA considers that the results are not indicative of a discharge from the sewage reticulation system for the following reasons: 1. ‘Thermotolerant Faecal Coliforms’ can be used as faecal pollution indicators as this bacteria occurs in warm blooded animals. Although faecal pollution indicators were present in the water samples, the levels are many orders of magnitude less than the levels in a raw effluent discharge; 2. Bacterial levels will be elevated in a waterway such as Timbara Creek following a storm event as it is closed off to the ocean for extended periods during which time urban stormwater runoff will elevate bacterial levels up to 20,000 colony forming units per 100 millilitres following a storm event. 3.Faecal coliform levels in sewage will be in the millions or tens of millions;Nutrient indicators including phosphorus and ammonia were present in the water samples at very low levels. Water contaminated with sewage will be polluted with high levels of nutrients.; 4. The EPA has reviewed the run time and effluent capacity level data for the sewage pumping station for the period from 13 March to 21 March which shows that the sewage pumping station did not overflow or exceed 35% of its capacity at any time during the period; 5. Council collected water samples on 20 March 2017 and found that the bacterial indicators in the creek had returned to very low levels. As detailed in several environmental reports of Eurobodalla creeks such an event is not at all unusual. The smell is more than likely hydrogen sulphide and the dead fish observed were most likely a result of the anoxic conditions that may have developed in the creek after it had been contained by a sand dune. Over the last two decades there is continued evidence of water ponding in Timbara Creek due to a natural build up of sand. This usually requires a good head of water to flush the culvert pipes under McLeod Road resulting in the scouring just witnessed. This scouring removes all forms of matter from the beach and from the creek as well Including decayed leaf matter that settles and decomposes on the creek bed releasing nutrients and chewing up available oxygen which causes the anoxic (total depletion in the level of oxygen) conditions. Those anoxic conditions then encourage phosphorus to be released from the creek bed while sulfate reducing bacteria further breakdown organic material generating hydrogen sulfide gas which is a colorless, flammable and extremely hazardous gas with a “rotten egg” smell that can smell like sewer. So when a creek such as Timbara Creek sits full for a period of time and is then opened as recently happened it further disturbs the sediments, promotes the release of more hydrogen sulfide gas and often causes a fish kill if there are fish and invertebrates present.
Above: Photo of the scouring made by the recent opening of the creek. It is alleged by Mr Sethi (who provided this photo) that the top layer of sand was placed in order to create a dam that would further contain the water in the creek to a flooding level. It was only through his continued questioning that the "dam" wall was finally broken by hand resulting in this scour.