Edwardes Lake wetland treatment system

Edwardes Lake Park is surrounded by housing and industrial estates. Stormwater running off these areas can carry sediment and contaminants with it, which can harm wildlife and lead to pollution of our local creeks, lakes and even Port Phillip Bay. To help improve the quality of stormwater from this area, the Edwardes Lake wetland treatment system was created in the 1990s.

The system works by collecting stormwater in the Leamington Street wetlands. These wetlands are very low lying and act as a flood retarding basin, slowing the flow of stormwater down. Plants in the wetlands capture large pieces of litter, sediments and other contaminants from the water. The smaller pollutants (such as oil, organic matter (anything that was once alive), small pieces of plastic, detergents and chemicals) are trapped in the wetland floor (bed layer). Bacteria and fungi break down the organic matter so the wetland plants can absorb nutrients from it, helping them to grow.

The treated stormwater drains slowly into Edgars Creek then into the ‘low flow bypass wetland’ which is next to Edwardes Lake on the north-west side. The flow and levels of water in this wetland can be controlled to increase the breakdown of sediments and contaminants. Large water plants, called macrophytes, capture nutrients and silt at their roots. Once the water has been treated it flows through subsurface (underwater) drains into Edwardes Lake, where it provides high quality habitat for water fowl, fish and other aquatic wildlife. Edwardes Lake’s main purpose is to store the treated water for irrigation purposes, but it also has a gross pollution trap on its western bank, which acts like a giant sieve to capture any large pieces of litter such as bottles and plastic bags.

The Edwardes Lake wetlands system consists of:

• Stormwater collected from local housing and industrial areas.
• Wetlands water treatment system including the Leamington Street wetlands, Edgars Creek and the low-flow bypass wetland. These all work to filter out sediments, litter and other contaminants from the stormwater.
• Edwardes Lake – a large capacity water storage lake which also provides habitat for wildlife and supports a large recreational green space for the community.
• Irrigation system for maintaining the lake’s parklands and other Council properties.
• Overflow system that can release water into Edgars Creek and finally into the Merri Creek.

1800s
The swampy valley of Edgars Creek was part of the traditional lands of the Wurundjeri people. The land was sold by the Crown in 1845 and a weir (low dam) was built across the creek in the late 1800s to enable rowing and boating at the lake.

Early 1900s
In 1914, Thomas Dyer Edwardes donated 34 acres of land to Preston Council for a park. In 1919, the weir was rebuilt by servicemen returning from the First World War. The weir created a swimming and fishing hole for the local community. Edwardes Lake Park was officially opened in 1920.

1950s-60s
Development of housing and industrial estates in Reservoir destroyed the lake’s natural vegetation. Although the lake was still used for swimming and boating, by the mid 1960s, fishing ended due to poor water quality.

1970s
Carp and domestic ducks (non-native animals) were replacing indigenous (native) aquatic species in the lake. The lake was drained several times to remove litter and contaminated silt.

1995
The sediment-trapping wetlands were created upstream from the lake to help improve water quality.

2002-2004
The gross pollutant trap was installed. Sediment removal and reshaping of the lake bed was undertaken to improve water circulation and reduce bacteria and algal growth.

2004
Planting of native species in the wetland areas was undertaken to improve local biodiversity (the range of plants and animals present) and park amenity.

2003-2005
The Edwardes Lake Park Neighbourhood Environment Improvement Plan (NEIP) was undertaken. The project included community engagement and water quality monitoring, as well as monitoring the effectiveness of the wetland water treatment system.

2017 onwards
Increasing the size of the lake to expand its water storage capacity is currently being considered by Darebin City Council. The Edwardes Lake Park Master Plan is currently in development.

Major works at Edwardes Park Lake have cost more than $3.5 Million to date. This has included:

• $2.5 Million from Darebin City Council
• $650,000 from Melbourne Water
• $532,500 from the Victorian Stormwater Fund

The Edwardes Lake wetland treatment system is visited by Darebin City Council every six weeks to remove litter and weeds and carry out planting. Regular ‘working bee’ community events are held to undertake more maintenance and planting. Annual frog and bird monitoring events are organised at the lake by local conservation groups such as the Friends of Edwardes Lake and Friends of Edgars Creek

The Edwardes Lake Neighbourhood Environment Improvement Plan (NEIP) was delivered by Darebin City Council between 2003-2005. It focused on engaging the community on issues around sustainability of the lake. The NEIP team worked closely with State Government, water authorities, neighbouring councils, community groups and local businesses to develop and deliver the plan.

Edwardes Lake Park is a large, well-loved parkland visited by over 135,000 people each year. It features free barbecues, playgrounds, exercise stations, a skate park, walking tracks and hosts the annual Darebin Kite Festival. The lake gives the park its character, providing an attractive wetland and bush landscape in an otherwise urban area. Studies have shown that public open space in urban areas can increase levels of physical activity in the community and have mental health benefits, which can help to reduce healthcare costs (Parks Victoria, 2017).

The lake and wetlands treatment system play an important part in reducing the risk of flooding in surrounding areas. Using the treated stormwater for irrigation of the parklands and other Council properties costs much less than it would to irrigate the grounds with tap water. This saves Council and rate-payers money, and preserve’s the community’s drinking water supply.

The Edwardes Lake wetland treatment system helps to slow the flow of stormwater running off local housing and industrial estates and stops it from running straight into the Merri Creek un-treated.

Slowing the flow of stormwater helps to prevent erosion (loosening of soil) of the creek banks and allows the water to be filtered in stages to remove sediment, litter and other contaminants. This helps to make sure that any water leaving the wetlands is much cleaner and healthier for aquatic life in the Edwardes Lake, Edgars Creek and Merri Creek. The wetland is part of the Edgars Creek and Merri Creek riparian wildlife habitat corridor, which supports indigenous (native) flora and fauna. Many animals call our local creeks home, such as platypus, rakali (native water rat), frogs, fish (such as the common galaxias) and birds (such as the sacred kingfisher). Much of the planting carried out in the wetlands has improved the habitat for local aquatic species as well as terrestrial (land-based) wildlife including birds, small mammals and reptiles.

Any stormwater that is discharged from Edwardes Lake into the Edgars Creek has been treated by the wetlands system, helping to improve the quality of water in the Merri Creek. This benefits the plants and animals that live in and around the creek – and those further downstream, in the Yarra River and Port Phillip Bay.

Darebin City Council acknowledges the Wurundjeri people as the traditional owners and custodians of this land and pays respect to their Elders past and present.

• Melbourne Water
• Victorian State Government

Other project partners in the NEIP included:

• Victorian Environmental Protection Authority
• Yarra Valley Water
• City of Whittlesea
• Friends of Edwardes Lake
• Friends of Merri Creek
• Merri Creek Management Committee
• Melbourne Metropolitan Fire Brigade
• VicRoads
• VicUrban
• Department of Sustainability and Environment