Protecting our waterways

Stormwater and stormwater pollution

Stormwater

Stormwater is rainwater that runs off roofs, roads, pavements, carparks, gardens and other surfaces. In the urban environment, this water is directed into gutters and into our drainage systems.

Pollutants in stormwater

When it rains the pollutants on our roofs, roads and pavements are picked up by the stormwater and washed into our drainage system. Stormwater may contain pollutants such as litter, excess nutrients, chemicals and sediments. Petrol, oils and heavy metals deposited by cars on our roads are also found in stormwater.

In Merri-bek, the best quality stormwater is rainfall captured directly from roofs, before it has the chance to pick up pollutants from the roads or other sources. This water may be reused by residents through fitting a rainwater tank and using it for garden watering or toilet flushing.

The problem with stormwater pollution

The drainage system is designed to take rainwater into the closest river or creek. Unlike sewage it usually isn't treated and in most cases anything that enters a stormwater drain is discharged directly into our rivers and creeks and ultimately into Port Phillip Bay.

The current system conveys the pollutants picked up by stormwater directly to our creeks and the bay. The pollution from stormwater causes many environmental issues such as algae blooms, fish and animal deaths, the build up of sediment and unsightly litter, and deteriorates the enjoyment experienced by our community interacting with the waterways.

In addition, in urban areas run off is generated far more often and in greater quantities when compared to the natural environment before development occurs. These more frequent and higher flows cause erosion of our waterways and alter the habitat of native species.

Water Sensitive Urban Design

Water Sensitive Urban Design integrates sustainable water management into the design of our urban areas. It focuses on conserving water, treating and reusing stormwater, and recycling waste water.

A key component of Water Sensitive Urban Design is reducing the pollution caused by stormwater by implementing raingardens, tree pits and other stormwater treatment measures such as stormwater harvesting.

Council is working with Melbourne Water, Yarra Valley Water and community groups to implement these treatment measures across Merri-bek.

Raingardens

A raingarden is similar to a regular garden, however it has been modified to help filter stormwater runoff before it enters the local waterways.

Installing raingardens result in cleaner creeks and rivers, and a healthier ecosystem for native plants and animals.

The key differences between a normal garden and a raingarden are:

• Raingardens are positioned to receive stormwater running off from hard surfaces such as a downpipe from a roof, paved areas or roads.
• Raingardens contain a number of different layers of soil and gravel beneath the surface. These layers help filter out the pollutants contained within stormwater.
• Raingardens are planted with specially selected range of plants, shrubs, grasses and trees. The plants in the raingarden can survive in very wet conditions following a rain event or without water for a long period during a drought.
• The layers of soil and gravel for filtration and planted with a combination of plants, shrubs and grasses, means that a raingarden reduces the amount of stormwater that would otherwise wash pollutants into the stormwater system and our rivers and creeks.

Tree pits

A tree pit is a special type of raingarden.

They contain the same layers of soil and gravel as a raingarden, however they have been planted with only a tree. This allows tree pits to be located in areas such as shopping strips or close to footpaths, where it may not be practical to have a larger raingarden.

Tree pits collect stormwater runoff from small car park areas or roads. The runoff filters through the tree roots and surrounding soil mix, trapping sediment and removing pollutants before flowing to the piped stormwater system.

How Council is contributing to the health of our waterways

Click on the fish symbol in the map below to find out more about Council projects.

Council, with support and funding from Melbourne Water's Living Rivers program, is delivering a number of Water Sensitive Urban Design projects in public spaces such as parks, streets and schools.

Passively irrigated street tree best practice guidelines. Moreland City Council, in conjunction with Melbourne University, have been investigating how passive irrigation may be used to improve street tree growth and reduce stormwater pollution. The findings and recommendations from a series of trials and research have been distilled into a set of best practice guidelines / tech notes (PDF 3Mb) aimed at improving the uptake of passively irrigated street trees and disseminating the findings into practice. We encourage the tech notes to be widely used and are looking for participants to assist in the monitoring of any designs based on the tech note designs – please contact Chris Szota at Melbourne University (cszota@unimelb.edu.au) for further information  Hosken Reserve, Coburg North. Stormwater havesting. Using stormwater to irrigate the sports grounds is the focus of a project at Hosken Reserve, Coburg North. The project diverts stormwater from an Council drain and cleans it for irrigation using a stormwater treatment wetland. The project will improves the reserve through landscaping works surrounding the wetland at the same time as reducing drinking water consumption by up to 8 million litres of water per year and helping to improve the water quality of Merri Creek. Wilson Avenue, Brunswick. WSUD. WSUD principles helped inform the design. The active heart of the space is ringed by a series of tree pits covered with timber decking. The whole site, as well as adjacent shop roofs drains into this ring of interconnected pits which removed the need for any surface drains. A strata cell system was used to link the pits beneath the paving and walls, greatly increasing the water holding capacity of the pits for improved tree health in the summer months. The design was awarded a $50K Living Rivers grant by Melbourne Water. Barrow Street, Brunswick. Water wise street tree trials Council has installed a trial of Water wise street trees (PDF 468Kb) in Barrow Street, Brunswick. These trees divert water from the road to the trees, providing them a water source. Designed in conjunction with Melbourne University, this innovative approach is expected to not only bring benefits to the health of the street trees but also improve the quality of stormwater runoff from the street before it reaches Merri Creek. The outcomes of the trial will determine how Council can improve the long term health of Merri-bek’s street trees.
Charles Mutton Reserve, Fawkner. Stormwater harvesting The stormwater harvesting project at Charles Mutton Reserve saves over 13 million litres of drinking water while at the same time helping to improve the water quality of Merri Creek and introduce a landscaped area to the reserve. The system captures stormwater from the stormwater drain system and treats it using the ‘raingarden’. This water is then used to irrigate the sports ground all year round, irrespective of water restrictions and drought events.
Anderson Road Shopping Strip, Fawkner. Streetscape raingardens Council has installed three raingardens as part of the recent redevelopment of the Anderson Road shopping strip. Stormwater flows from the footpath, carpark and road into the raingardens to be filtered from pollutants, such as litter, oil, petrol and nutrients, before it flows to Merri Creek. The raingardens also provide a water source for the plants, improving the health of the plants and reducing the amount of watering required.
Michael Street, Brunswick. Streetscape raingardens Four tree pits and two raingardens have been constructed within this streetscape upgrade in Brunswick. The footpath widening created space for the tree pits and raingardens that filter stormwater runoff from the road, roofs and footpath before it flows to our creeks. The trees also provide much needed shade and greenery in the area, reducing the urban heat island effect and making Brunswick a cooler place to be.
Sewell Reserve, Glenroy. Stormwater harvesting A stormwater harvesting project which captures water and reuses it as well releasing cleaner stormwater to our creeks. The stormwater harvesting project at Sewell Reserve saves water and helps to improve the water quality of Westbreen Creek. It saves 5 million litres of drinking water per annum and releases 30 million litres of cleaned stormwater to the creek every year. The water harvested is used to irrigate the sports ground all year round, irrespective of water restrictions and drought events. This is a great outcome for the sporting community of Glenroy.
Major Road Shopping Centre, Fawkner. Streetscape raingardens Council has installed four tree pits along the shop fronts and two raingardens at this small shopping strip. Stormwater flows from the pipes on the shop roofs and into tree pits to be filtered from pollutants before entering our waterways.
Snell Grove, Oak Park. Streetscape raingardens Eleven tree pits and four raingardens have been installed on both sides of this bustling shopping strip in Oak Park, adding some greenery while filtering the stormwater. The raingardens are strategically positioned to receive stormwater as it flows downwards from the top of the shopping strip.
O'Hea Street, Coburg. Streetscape raingardens A number of raingardens have been installed along this busy thoroughfare filtering sediments before they enter our waterways. The five raingardens along O’Hea Street are an attractive addition to the area. The installation of these raingardens is one of the many initiatives Merri-bek City Council is implementing to improve stormwater quality across the City.

How you can get involved

Council is continuing to undertake Water Sensitive Urban Design projects in Merri-bek. Your understanding of why Council is undertaking these projects and support for implementing raingardens in our municipality goes a long way to helping Council protect our waterways.

Council also runs and supports a number of community planting days across the municipality each year. On these days local residents to come together to plant trees, shrubs and groundcovers to improve our parks and creek environments, particularly along local waterways.

At the household level, if you're interested in installing your own raingarden, visit the Melbourne Water Raingardens page for further details.