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Dandenong Catchment

Land Use

Urban

Rural

Forest

Water Quality Index

Very Good

Good

Fair

Poor

Very Poor

See the ‘Dandenong Catchment’ page for a detailed description of the catchment.

Report Card for July 2014 – June 2015

This Report Card provides an overview of water quality in the Dandenong catchment from 1 July 2014 to 30 June 2015. The quality of the water was given an overall score by combining the results of six standard water quality parameters: nutrients, water clarity (turbidity), dissolved oxygen, salinity (conductivity), pH (acidity/alkalinity) and metals.

In 2014–15, water quality in the Dandenong catchment was ‘Very Poor.’

Summary Table: The table below shows the percentage of the Dandenong catchment that falls into each scoring category. See scoring method for more information.

Area Score
0%

Very Good
Near-natural high quality waterways

2%

Good
Meets Victorian water quality standards

Near naturally forested area at the base of Mt Dandenong

0%

Fair
Some evidence of stress

0%

Poor
Under considerable stress

98%

Very Poor
Under severe stress

Small streams in urban and industrial areas

The routine monitoring at 17 sites gives us information for about 71 per cent of the catchment. The remaining 29 per cent of unmonitored catchment is a mix of rural and urban land use, which would typically score as ‘Very Poor’ in this region.

See the Monitoring Programs page for changes to the monitoring program.

The section 'Changes over time’ compares these annual index scores and indicators with the Dandenong catchment’s scores from previous Report Cards (since 2000). Results can also be compared to other catchments.

Site-specific details about parameters can be accessed via the map.

What does this mean?

Water quality in the Dandenong catchment is ‘Very Poor’.

Urban and industrial land use dominates much of the Dandenong catchment. Runoff from these areas carries pollution to the waterways, which reduces waterway health. Concentrations of nutrients and metals (e.g. copper, lead, zinc, chromium) are often high due to runoff from industrial areas and roads.

Historically, many waterways in the Dandenong catchment were straightened or concrete-lined to increase their effectiveness in draining away water and reducing floods. However, this has removed natural meanders in the waterway and destroyed a lot of stream habitat, which, along with polluted run-off has decreased water quality in these waterways. For example, clearing trees around a waterway reduces shade and increases water temperature, which decreases dissolved oxygen

The exception to this ‘Very Poor’ score is the relatively undisturbed monitoring site on the edge of the forest in the upper reaches of the Dandenong catchment (see Dandenong Creek, Doongalla Forest). At this location, the WQI scores ‘Good’ because the environment is closer to its natural state. This was the only monitoring location in the Dandenong catchment with low metal concentrations, demonstrating the source of these inputs to be from industrial and urban areas within the catchment.

Despite the catchments scoring ‘Very Poor’, these waterways continue to sustain considerable populations of fish, frogs and birds. The region’s significant wetlands (Edithvale-Seaford wetlands) are recognised for their valuable diversity of waterbirds under the Ramsar Convention).

Events

Short-term environmental and extreme weather events can impact water quality in waterways. Long-term dry spells can result in reduced river flows, increases in salinity and algal blooms, while heavy rainfalls can cause flooding, river bank erosion, and wash sediments, nutrients and pollutants into waterways.

Below average rainfall was observed in 2014–15. The Bureau of Metrology (2016) noted just three days during the year when significant rainfall (between 25 – 29 mm) was recorded.

Outside of these dates, no significant environmental or weather events were recorded for the period that would have significantly affected water quality.

Bar chart of WQI and indicator scores for Dandenong Catchment. Bar chart of WQI and indicator scores for Dandenong Catchment.

Dandenong Creek, Maroondah. Source: Melbourne Water Dandenong Creek, Maroondah. Source: Melbourne Water

Drain stencilling and litter awareness activities in Belgrave. Source: Melbourne Water Drain stencilling and litter awareness activities in Belgrave. Source: Melbourne Water

Changes over time

Looking at the scores for the Dandenong catchment going back to 2000, there is a general trend of ‘Very Poor’ water quality scores.

The water quality has most likely been influenced by urban and industrial development in the catchment over the past two decades, particularly around Hallam, Cranbourne, Lynbrook and Berwick.

Some sites have shown very slight improvements since the drought broke in 2010, but scores have remained ‘Very Poor’ due to high concentrations of metals and nutrients that originate in this catchment’s large industrial and urban areas.

Plot of WQI history for Dandenong Catchment Plot of WQI history for Dandenong Catchment

Actions

Management objectives across the Dandenong catchment aim to strike a balance between managing for flood mitigation and protecting environmental values. Improvements in water quality can be difficult to achieve in catchments with heavy industrial and urban development.

Pollutants are often transported into waterways from diverse sources spread across the catchment. The implementation of projects designed to reduce stormwater inputs such as installing water-sensitive urban-designed rainwater tanks, raingardens and roadside swales (vegetated ditches designed to collect runoff) can help to improve water quality in urban waterways.

What's happened?

The Government, authorities and community have implemented the following initiatives to improve waterway health in the Dandenong catchments:

Melbourne Water

  • Planted 15 km of native vegetation; maintained 153 km of native vegetation; and installed 0.2 km of stock-exclusion fencing.
  • Removed 2100 cubic metres of silt and sediment; and removed 2400 cubic metres of litter and debris from waterways that were affecting basins in the Dandenong catchment.
  • Partnered with local councils to construct water-sensitive urban-designed rain gardens, bioswales and other integrated water management projects to capture stormwater for treatment and reuse
  • Worked with the local council to upgrade and improve streamside habitats and control erosion along Dandenong Creek.
  • Undertook fortnightly blue-green algae monitoring during the summer period at seven sites.
  • Undertook weekly monitoring at five sites to better understand recreational health risks.
  • Worked with Councils to upgrade drainage assets and retarding basins to improve flood protection.

Environment Protection Authority Victoria (EPA)

  • The $2 million 2014-2017 Litter Hotspots grants program was introduced by EPA in 2014. This program is led by the Melbourne Waste and Resource Recovery Group, working with local councils and community groups to find local litter solutions.
  • Investigated pollution events in Eumemmerring Creek and Mordialloc Creek.

For more information about projects and works for the Dandenong catchment in 2014–15, please see the Melbourne Water Waterways Local Updates.

What's planned

A number of priority areas and actions have been identified in the Dandenong catchment to build on existing projects and initiatives. These include:

  • A five-year pollution prevention project plan was formulated as part of the Enhancing our Dandenong Creek project (EODC) which included a literature review of behaviour change programs for stormwater pollution management in the Old Joes Creek catchment.
  • Melbourne Water is implementing their ‘Healthy Waterways Strategy and Stormwater Strategy’. These strategies cover the five years from 2013–14 to 2017–18 and contain information about planned actions to improve the health of rivers and creeks in the Dandenong catchment.
  • Improving streamside and wetland vegetation across the catchment, including within the Ramsar-listed Edithvale-Seaford Wetlands
  • Continuing EPA’s hotspot investigations across the catchment.
  • Roll out of the Litter Hotspots grants program.

Compare to other Catchments

The following figures show a comparison of scores for each identified water quality indicator in the catchments and Port Phillip Bay.

Diagram of nutrient score history for catchments and bay

Diagram of oxygen score history for catchments and bay

Diagram of water clarity score history for catchments and bay

Diagram of salinity score history for catchments and bay

Diagram of score history for catchments and bay

Diagram of metals score history for catchments and bay

Program Partners

Department of Environment and Primary Industries Environmental Protection Agency Melbourne Water