Yarra Inputs – Tracking Sources of Faecal Pollution
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YARRA INPUTS – TRACKING SOURCES OF FAECAL POLLUTION Publication 1057 March 2007 presence of bacterial contamination presents a INTRODUCTION potential public health risk to recreational users. The Yarra River has shaped Melbourne’s While many gains have been achieved over the past development and growth, supporting industry and few decades, the Government’s Yarra River Action tourism, and is highly valued as an environmental Plan identifies more work that needs to be done to and recreational asset. improve water quality further. Two million Melburnians live and work in the Identifying the types of faecal contamination and suburbs that drain into the Yarra River. Growing how and where it is entering the Yarra River is population, expanding urban development and fundamental to ongoing improvements in intensification of agriculture activities in the recreational water quality. This information is catchment are all placing increasing stress on the necessary to allow the direction of management river and directly impacting on its water quality. action and resource investment to areas where they The Yarra River is being used more and more for a will have the maximum benefit in reducing faecal range of water-based recreational activities, and the contamination inputs. Figure 1: Yarra inputs – drains, tributaries and river sample sites 1 YARRA INPUTS – TRACKING SOURCES OF FAECAL POLLUTION EPA Victoria and Melbourne Water are leading a IDENTIFYING THE SOURCES three-year Yarra River Action Plan project to locate Bacterial levels start to climb noticeably in the and remove key sources of faecal pollution entering middle and lower reaches of the Yarra River and it is the middle and lower reaches of the Yarra River. in these areas that water-based recreational This report provides a summary of the first-year activities become more frequent. The screening screening investigation. This was undertaken to investigation was carried out to identify the most identify which of the many stormwater drains and significant sources of faecal contamination in this tributaries entering the Yarra River: stretch of the river. • contribute significant levels of faecal Ten major metropolitan tributaries and 29 contamination to the river stormwater drains flow into the Yarra between • require further detailed investigation to Warrandyte and Docklands. Of these, there is a pinpoint the sources and direct works to significantly higher density of stormwater drains in remove these sources. the lower reaches of the Yarra River downstream of Kew. SOURCES OF CONTAMINATION Samples were collected from these tributaries and drains, at or near the point of entry into the Yarra Melbourne’s extensive drainage system carries River, as well as at 13 locations in the river itself stormwater from our streets and buildings through a (Figure 1). Sampling occurred on six days during late series of gutters, pipes and drains and discharges it 2005, in both wet and dry weather conditions. into rivers and creeks. The city’s extensive sewerage E.coli indicator bacteria were measured at all sites, system carries sewage through another series of along with other water quality indicators such as pipes to sewage treatment plants. nutrients. Flow rates entering the river were In dry weather, potential sources of faecal measured or estimated, to provide an indication of contamination include sewer blockages, seepage of the relative contributions to the faecal load in the sewage from the system, and cross-connections river from the various input tributaries and drains. between sewerage and stormwater pipes. Poorly Where bacterial levels were found to be elevated, operating septic tanks and animal inputs are also the faecal sterols method (developed by CSIRO) was potential contributors. also employed to assist in identifying whether In wet weather, the amount of contamination in the human faecal contamination was present in the river may increase from a number of sources, drains and tributaries. One faecal sterol in particular including increased run-off from stormwater drains, – coprostanol – is a biomarker of human surface run-off direct to the river and sewer contamination, constituting approximately 60% of emergency relief structures allowing temporary the total sterols found in human faeces. Some of the discharge of sewage to waterways during heavy Yarra River sites were also analysed for faecal storms. EPA Victoria 2 YARRA INPUTS – TRACKING SOURCES OF FAECAL POLLUTION sterols, regardless of their measured bacterial human faecal contamination. Some drains showed levels. very high proportions of human faecal matter compared to other sources of bacterial contamination on one or more sampling days. WHAT WE FOUND The results clearly indicate a number of drains, such The results (in the Appendix) showed that bacterial as Harper Street, Elizabeth Street and Kew, as levels entering the river varied considerably, both significant sources of bacterial contamination. between the sites and across the different sample Others show little signs of contamination – for dates at the same site. There are, however, some example, Banyule, Yarra Park and Federation Square general comments that can be made. drains. There are also a relatively large number of In dry weather, many of the drains had much higher drains that show a great deal of variability in the E.coli concentrations than the tributaries and the E.coli, flow or human faecal biomarker results. river itself. There was also much more variability between samples taken from individual drains. IDENTIFYING PRIORITY SOURCES Because of the generally higher flows in the tributaries compared to the drains, the E.coli load An assessment of the results from the screening for the tributaries was often relatively higher in dry investigation, and historical information where weather. Despite this, the E.coli concentration in available, was undertaken to identify the tributaries many of the tributaries was often similar to, or less and drains that are significant sources of faecal than, the concentration in the river, so the effect of contamination to the Yarra River. the tributary input was often only minor. The assessment considered the results based on the Rainfall run-off is known to contribute to elevated premise that, if our stormwater and sewerage bacterial levels. In wet weather, both the drains and systems are performing well: tributaries generally had much higher • in dry weather, there should be little bacterial concentrations and loads of bacteria than in dry contamination present in drains and weather. Again, the drain samples showed the most tributaries, and evidence of human faecal variation between the sampling events. With higher contributions should not be found flows on wet-weather sampling days, the tributaries • in wet weather, bacterial levels will increase made much greater relative contributions of faecal from a range of sources, but evidence of load than the drains. As would be expected, the wet- human faecal contributions should only be weather samples from the mainstream Yarra River found in storm events, when sewer sites had higher E.coli levels than the dry-weather emergency relief structures activate (allowing samples. temporary discharge of sewage to Most drains recorded the faecal biomarker waterways). coprostanol at a level indicating the presence of Information Bulletin 3 YARRA INPUTS – TRACKING SOURCES OF FAECAL POLLUTION The determination of priorities was based on an • Bulleen North Main Drain analysis of the following factors: • Prahran Main Drain • presence of high levels of E.coli on more than • Fairfield Main Drain one occasion • Glass Creek Main Drain • the load or volume of bacterial contamination • Gardiners Creek contributed to the Yarra River • Koonung Creek • the change in bacterial levels that this load would cause in the river itself • Darebin Creek. • biomarkers of human faecal contamination found in significant proportions relative to the PROGRESS OF PRIORITY total bacterial levels INVESTIGATIONS • the significance of results in dry weather Intensive follow-up investigations are under way on (when there should be little contamination) a number of the priority drains that are easily and wet-weather conditions accessible: • for the tributaries where there was monitoring • Harper Street Main Drain data available, the number of years of • Kew Main Drain elevated E.coli levels. Salt Creek Main Drain From this process, 12 priority stormwater drains and • three tributaries (listed below) have been identified. • Hawthorn Main Drain Further detailed follow-up investigations on each of • Locksley Road Main Drain these drains and creeks is required in order to identify where faecal contamination is being • Bulleen North Main Drain introduced into these systems. • Prahran Main Drain. • Harper Street Main Drain This involves walking through the larger stormwater drains, taking samples inside the drains and using • Elizabeth Street Main Drain closed circuit television for the smaller stormwater • Kew Main Drain drains. Councils and water retailers are assisting • Princes Bridge Drain with these investigations. • Salt Creek Main Drain An investigation of the Elizabeth Street and Princes Bridge drains has also commenced. The lower • Hawthorn Main Drain sections of these drains are continuously flooded, • Locksley Road Main Drain cannot be safely entered, and require a different • Porter Street Main Drain range of methods. A ‘toolkit’ of methods is being EPA Victoria 4 YARRA INPUTS – TRACKING SOURCES OF FAECAL POLLUTION