Last week, I found a small public notice in the local newspaper. Recycled water from the local sewage plant is usually used on golf course, but due to lots of rain, they couldn’t accept anymore. So Barwon Water was proposing pumping into Bruce’s Creek to prevent their storages from overflowing. Not a nice thought. While it’s not very smelly, Class C recycled water can have a very high phosphorus levels and the long term impact on the creek’s ecology could be dire.
With my trusty WaterWatch kit I headed off to see what was going on. On August 2nd, there was no flow in the creek upstream of the potential discharge site and the water below the town was low in phosphorous. But three days later, it was a different story. This time I took my mountain bike and headed cross country to find the pipeline that Barwon Water had laid between the sewage treatment lagoons and the creek. Now the entire flow in the creek was recycled water, slowly bubbling its way out of the PVC diffuser and heading downstream.
The phosphorus reading was 8.3 mg/L. Lakes in the Western District which have been used for dumping sewage for years sometimes get as high as 3 mg/L. Flowing waters should be around 0.1 mg/L. Too much phosphorus can cause algae and aquatic weeds to grow excessively, making it harder for other species to survive, which is why washing powders are often advertised as low P. A week after the discharge started, the effluent had yet to reach the bridge below Bannockburn but it had pushed a wave of salt water ahead, affecting the creek’s complex hydrology. Barwon Water are doing their own monitoring but have not shared their data.
Why is this happening? Back in 1997, when Barwon Water built the sewage treatment plant, they argued that this would protect the creek from pollution from septic tanks. It did make the town less stinky, but it also allowed more houses to be built, and now the sewage plant is struggling to cope.
The answer? In the short term, the effluent could be trucked to a nearby sewer – it’s not a huge volume. In the longer term, people in Bannockburn and all over Victoria need to use less water. It’s not just our sewage but all the water we use in our homes which ends up in sewage treatment plants, and potentially in creeks. Ultimately, the solution is to stop treating our rivers and creeks as drains.
Stuart McCallum is a commitment advocate for rivers, creeks and bushland in the Bannockburn area.