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Yarra Watch 2018–19 Summer Highlights Report

Swans on the Yarra River

Swans on the Yarra River in Melbourne. Source: Melbourne Water

The Yarra River is widely used for recreational activities such as boating and swimming throughout summer.*

Environment Protection Authority Victoria (EPA), in partnership with Melbourne Water, runs the Yarra Watch program, which forecasts and monitors recreational water quality at four sites along the Yarra River – Kew, Warrandyte, Healesville and Launching Place. Water quality is determined by the levels of bacteria in the water, which can pose an increased risk of disease for people coming into contact with the water.

The summer season ran from 1 December 2018 until 11 March in 2019.

* Please note that it is illegal to swim in the Yarra downstream of Gipps Street, Abbotsford. Kew at Chandler Highway Bridge is the only Yarra Watch site in the Lower Yarra where it is legal to swim.

Fast Facts

  • Based on sampling over the summer, three out of four Yarra sites met end-of-season long term water quality objectives for swimming.
  • 49 per cent of water forecasts issued over summer were Good, 32 per cent Fair and 19 per cent Poor (in 2017-18 summer, 42 per cent were Good, 31 per cent Fair and 27 per cent Poor). Forecasts are based on observed and forecast weather, water quality history, weekly water sampling results and current pollution alerts issued.
  • One water quality alert was issued for the Yarra River over summer (when EPA receives reports of pollution or algal blooms in the Yarra River). Some tributaries to the Yarra River, such as Scotchmans and Darebin Creeks were issued with multiple alerts.
  • Forecasts were provided to over 8,600 followers on Twitter.

How did swimming spots along the Yarra perform?

Table 1: Results of water quality monitoring at Yarra River swimming spots

 Location  Objective
 Launching Place  ✗
 Healesville  ✓
 Warrandyte  ✓
 Kew  ✓

Three out of four Yarra River swimming spots met the water quality objective for swimming this summer (Table 1).

Warrandyte had the best overall water quality of all Yarra swimming spots this season.

The one Yarra site that did not meet the objective was Launching Place. It does not mean this site was unsafe for swimming the whole season, but Launching Place did experience a higher number of days with poorer water quality. Poor water quality may be due to a range of pollution sources such as leaking septic tanks and animal faeces (e.g. agricultural livestock and birds).

All sites meet objectives for secondary contact recreation (i.e., boating, rowing, canoeing).

Yarra water quality has been variable in recent summers

Table 2: Water quality trends for swimming at Yarra River sites.

 Swimming objectives met?

  2014-15 2015-16   2016-17  2017-18 2018-19   Water quality trend
Launching Place  ✗  ✗  ✗  ✗  ✗  No change
Healesville  ✓  ✗  ✓  ✓  ✓  No change
Warrandyte  ✓  ✓  ✓  ✓  No change
Kew  ✓  ✗  ✓  ✗  ✓  Variable

Water quality in the Yarra River has varied over the last five years. Stormwater pollution after rain has been the most common factor determining whether a Yarra River site meets the objective for swimming (Table 2). 

Warrandyte has been consistently the best location for swimming in the Yarra River.

Healesville and Kew vary between summers between 2014-15 and 2018-19, however Healesville has been consistently good over the past three summers. Launching Place has continually not met overall season objectives. This means bacterial levels in water at these sites have, from time to time, posed an increased risk to swimmers. Bacterial pollution was most often due to stormwater runoff entering the river. We note that our monitoring results may pick up more bacteria if the scheduled sampling happened directly following a rain event. However, bacteria may also be present during dry weather as a result of faecal contamination from a range of animal and human sources in the Yarra’s rural and upper catchment (see ‘Water quality and health for swimmers’ section for more information on faecal sources). EPA Victoria will be working with Melbourne Water to better understand and track pollution sources in the mid to upper Yarra River (e.g. Launching Place and Healesville) where dry-weather pollution is known to occur.

What information do we gather and report about the Yarra River?

The information we report on during the summer months includes the following:

  • Water quality forecasts: 
    • Reported twice daily on this website and EPA twitter.
    • Forecasts of Good, Fair or Poor are given for each location to help Victorians make decisions about using the water for recreational use.
    • Reports are based on weather forecasts, observations and warnings, water quality history, and weekly water sampling results.
  • Weekly water quality monitoring:
    • Samples are analysed for the presence of bacteria called E. coli. The presence of E. coli is an indicator of other bacterial and pathogens that may make water unsafe for recreational use.
    • If it’s not considered safe to swim due to increased risk of exposure to bacteria and pathogens, the public are notified on the Yarra and Bay website and Twitter.
    • EPA works with local councils and water authorities to investigate the source of water pollution.
    • Water quality samples are used to assess whether the site has met the end-of-season water quality objectives for swimming.
  • Alerts about pollution incidents, fish deaths and algal blooms:
    • Water quality alerts are given all year round.
    • Alerts are based on reports from the community, businesses and government, and EPA or other responding agency.

Pollution can be reported at any time to EPA on 1300 EPA VIC (1300 372 842).

How accurate were Yarra Watch water quality forecasts?

The accuracy of Yarra Watch forecasts was measured by comparing weekly bacterial water quality sampling results to the corresponding morning forecasts (10am) on the same day for each location. 

This summer:

  • 91 per cent of forecasts provided appropriate advice about whether it was safe to swim. That is, when actual water quality was Good EPA issued either Good or Fair forecasts. When water quality was Poor EPA issued either Poor or Fair forecasts.
  • 87 per cent of good and Poor forecasts correctly predicted the actual water quality.
  • Forecasting occasionally misses poor water quality. Of the four Poor water quality samples that occurred on Wednesday's over the summer, one of the samples were issued with a Good forecast. This equates to <2 per cent of total forecasts issued over summer. The other three Poor water quality samples were issued with two Fair and one Poor rating, which are appropriate ratings to protect health as they advise caution.
  • Forecasting can provide false alarms. Of the Good water quality samples over the summer, <8 per cent were issued with Poor forecasts.

For more information on how we generate forecasts and the accuracy of our forecasting go to Generating forecasts for Beach Report and Yarra Watch.

Water quality and health for swimmers

Increased risk of illness primarily occurs when water is contaminated with human or animal faeces. Yarra Watch monitors E. coli in the River, which is a bacterium that is an indicator of faecal pollution. Faeces may carry any number of disease-causing organisms (pathogens) such as bacteria and viruses, with gastroenteris being the most common illness experienced by swimmers.

In wet weather, rain can carry pollution from residential, industrial and agricultural areas into the Yarra. The level of pollution, including human and animal faeces in stormwater can vary according to the duration and intensity of rain, and depends on land use or activities in the Yarra's large catchment.

Human faecal contamination in the River still occurs occasionally with dry weather sewer spills and sewage overflows during storms (e.g. late December 2016) entering the Yarra. The extent of human faecal contamination in the Yarra is comparable to studies in other parts of the world.

High pathogen levels in stormwater run-off to the river can be caused by sewerage and septic tank leakages, cross-connections between sewerage and drainage systems, or litter and animal faecal waste (for example, bird and dog droppings) entering drains. Additionally, when there have been heavy rain events, such as in late December 2016, sewage overflows from emergency relief structures can also increase bacterial levels in the river.

In dry weather, potential sources of faecal contamination in the river include:

  • leaking sewer infrastructure (particularly where it is above the stormwater drainage system)
  • cross-connections between sewerage or septic tanks with stormwater drainage systems

  • poorly-operating septic tanks and onsite sewage treatment plants

  • animal faeces from birds, livestock accessing the river or its tributaries, or runoff of livestock faeces during periods of irrigation

  • sediment that may contain pathogens resuspended during environmental-flow releases.

Increased bacterial levels can be expected as a result of these inputs, however, they are usually short-lived.

What can influence water quality and forecasts during summer?

During rain events, pollutants wash down stormwater channels and into the Yarra River, which increases the risk of swimming at nearby swimming spots.

When it rained this season, Yarra Watch informed the public by issuing a water quality forecast of Poor and advising people to avoid swimming near stormwater outlets after rain.

Extended periods of Poor forecasts were mainly issued during periods of heavy rain; these occurred around mid-December 2018. 

Swim advisories and other water quality alerts issued over summer

Swim advisories are issued if there are high bacterial levels found during dry weather, when people are more likely to use the river for swimming. This summer, there were no swim advisories issued for the Yarra based on weekly sampling at the four swimming spots. 

There was one water quality alert issued for the Yarra River based on reports to EPA from the public and businesses:

  • An alert was issued on 18 February as Melbourne Water was doing a ‘summer fresh’ water release in the Yarra River which involved water released to mimic the rivers natural flow patterns and improve water quality. The release was from 18 February to 1 March. River levels were expected to rise up to 40 cm on the main stem and up to 60 cm in Watts River during the release. The alert was removed once the summer fresh finished.

Alerts are removed after the pollution could not be detected or was no longer visible. Pollution of rivers and creeks can be difficult to investigate as EPA relies on timely public reports of pollution and for the pollution to still be occurring when EPA officers arrive at the scene. Pollution should be reported to the EPA hotline on 1300 EPA VIC (1300 372 842).

Future directions

EPA Victoria will continue to work with Melbourne Water to better understand and track pollution sources that cause water quality to be unsafe for swimming. The focus of this work will be on the mid to upper Yarra River (e.g. Launching Place and Healesville) where dry-weather pollution is known to occur.

For more information on how we generate forecasts and the accuracy of our forecasting go to Generating forecasts for Beach Report and Yarra Watch.

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