About The Wetlands

Why an Urban Wetland?

The need for the Urrbrae Wetland emerged in the early 1990s when the City of Mitcham Council
investigated ongoing flooding problems along Cross Road. It is here that two large pipe systems joined into
a single pipe under Cross Road and the stormwater flowed into the Patawalonga outlet and then into the St Vincent Gulf at Glenelg. In July 1993, a study revealed that the major stormwater pipes of this catchment area could not handle the increased volume of runoff caused by expanding local urban development. Hard surfaces such as roads, roofs, and paved areas prevented water from soaking into the ground, leading to frequent flooding of local streets and the farmland of Urrbrae Agricultural High School.

To address this issue, plans were developed to construct a water retention basin by diverting stormwater
into a purpose-built wetland. This system would temporarily hold excess water and release it gradually
through an outlet pipe into the existing drainage network, reducing the risk of flooding along Cross Roads.
The council and the school formed a partnership, enabling the wetland to be located on the grounds of
Urrbrae Agricultural High School, ensuring that the conditions of the “Deed of Gift” were respected and that the land continued to be used for agricultural education.

Funding for the construction of the wetland was provided by the City of Mitcham, the Department of
Transport, and the Patawalonga Catchment Water Management Board. The land, owned by the
Department of Education, remains part of the school, while management responsibilities are shared. The
City of Mitcham oversees the flood mitigation system, Urrbrae Agricultural High School manages the
educational use of the site, and a volunteer group known as the Friends of the Urrbrae Wetland takes
responsibility for vegetation and some general grounds maintenance.

The wetland was designed not only as a functional drainage solution but also as an ecological restoration
project. Efforts were made to recreate the natural landscape, flora, and fauna of the area as it existed priorto European settlement in 1836. Native species were reintroduced through carefully managed programs, transforming the site into a thriving habitat within an urban setting.

The development of the wetland as an educational centre was driven by the legacy of Peter Waite, a
philanthropist and prominent agriculturalist who donated his property to South Australia for the purposes of agricultural education and research. This ensured the wetland would serve as a place of learning for future generations. Today, it is used by Urrbrae Agricultural High School, local primary and secondary schools, TAFE institutions, the University of Adelaide’s Waite Campus, and various community groups.

The construction of the Urrbrae Wetland and its Learning Centre commenced in 1996 and were officially
opened by the Premier John Olsen April 1997, marking the completion of a project that successfully
combined environmental management, education, and community cooperation. Since then, it has become a widely recognised model for an urban wetland, demonstrating how cities can address environmental challenges while creating valuable spaces for education and biodiversity.

Our Vision Science with Practice
To inspire and empower people to understand, value, and protect wetlands and the natural
environment through education, engagement, and sustainable action.

Objectives

• Deliver engaging curriculum-based programs that inspire students to adopt sustainable
  values and practices.
• Build understanding of human impacts on the environment and foster a deeper appreciation
  of the functions, benefits, and significance of urban wetlands.
• Provide meaningful, hands-on learning experiences that increase awareness and
  appreciation of the natural environment and urban environments like wetlands.
• Equip and empower students and visitors with the skills, knowledge, and confidence to take
  positive action towards a more sustainable future.
• Foster collaboration through communication technologies and partnerships by connecting
  Urrbrae Wetland with schools, universities, and community organisations to support
  improved sustainability and conservation outcomes.

The Wetlands Today

The wetland is visited by over 6000 people including students from kindergarten to tertiary levels and various community groups each year. These visits provide opportunities to learn about how the wetland works as well as the importance of the natural environment surrounding the wetlands.

The wetland also has several Open Days a year which are run by their dedicated volunteer group. These provide any members of the community the opportunity to enjoy and discover the wonderful environment of this unique wetland.

For more information about go to bookings

Copying Nature Through Design

The Urrbrae Wetland is a permanent, constructed wetland designed to mimic many of the functions of a
natural wetland. Surrounding the main wetland are several ephemeral ponds, which fill after large rain
events and dry out during summer; demonstrating the seasonal nature of many natural wetlands.

The Urrbrae Wetland consists of four main water bodies:

• The Main pond – holding capacity of approximately 13.5 million litres of water
• Two sedimentation ponds – together hold approximately 1.2 million litres
• Overflow (Top-up) dam – holds approximately 3 million litres

When full, the main pond reaches a depth of up to 3 metres. Together, these water bodies enable the
wetland to function as both a flood mitigation system and a natural stormwater treatment facility.

Flood Prevention
The wetland can store approximately 17.7 million litres of water—more than seven Olympic-sized
swimming pools. During major rainfall events, the ephemeral ponds and surrounding floodplain area at the Urrbrae Wetland site provide additional storage capacity of up to 17 million litres.

Each year, between 300 and 400 million litres of stormwater pass through the wetland, significantly
reducing the frequency and severity of local flooding.

Improving the Design
The wetland has evolved since its construction. Originally, stormwater flowed directly into the main pond. Students from Urrbrae Agricultural High School conducted depth surveys of the pond and discovered that sediment accumulation had reduced the maximum depth from 3 metres to 2 metres in just five years.

As a result of these findings, two sedimentation ponds were added in 2003. These ponds capture sand, silt, and other small debris before water enters the main pond, improving water quality and extending the lifespan of the wetland by preventing excessive sediment build-up in the main pond. This reduces the need for costly sediment removal and helps maintain the pond's optimum water-holding capacity.

The Big Picture
Although the wetland covers only about 6 hectares, it receives water from a catchment area of
approximately 380 hectares. This means that rainfall from a large surrounding area can eventually flow
into the wetland, carrying in sediments, nutrients, litter, and other pollutants.

Before the wetland was established, stormwater flowed directly through drainage systems into Brownhill
Creek, the Patawalonga Basin, and ultimately the Gulf St Vincent. Today, the wetland intercepts and treats much of this water through natural processes including sedimentation, filtration, nutrient uptake, organic oxidation, and ultraviolet sterilisation.

Cleaning the Water

The wetland improves stormwater quality through a series of processes:

• large concrete blocks – Stormwater enters the wetland through two inlet drains. The blocks slow
  the flow of water, reducing its energy and allowing sediments and pollutants to settle more
  effectively.
• Trash racks – Filter out large debris and litter that washes in with the stormwater.
• Sedimentation ponds and rocks – As the water slows down, sand, silt and other suspended particles
  settle to the bottom of the sedimentation ponds.
• Flocculation – Fine suspended particles, including heavy metals, salts and some bacteria, clump
  together into larger particles called flocs. These heavier particles settle to the bottom of the
  sedimentation ponds, where they can be removed when the ponds dry out during summer.
• Riparian vegetation – Reeds and sedges help remove pollutants such as nutrients, salts and some
  heavy metals from the water. Their roots trap fine particles while microorganisms living on the
  roots and stems break down organic matter, oils and other contaminants. Nutrients such as nitrates
  and phosphates are absorbed by the plants and incorporated into new growth.
• Oxygenation and Oxidation – Aquatic plants release oxygen into the water through photosynthesis.
  This oxygen supports bacteria that break down organic matter and other natural wastes within the
  wetland.
• Evaporation – Some volatile hydrocarbons from fuels and oils evaporate from the open water
  surface.
• Ultraviolet (UV) radiation – Exposure to sunlight can reduce the survival of some bacteria and
  other pathogens in shallow, open water.

Creating a Safe Home for Wildlife

The Urrbrae Wetland provides important habitat for a wide range of native species, including more than 50 species of birds, reptiles, amphibians, fish, and aquatic macroinvertebrates.

More than 100 species of locally native plants have been established throughout the site. These species are considered endemic to the region and are believed to have occurred naturally before European settlement in 1836.

The vegetation has been designed to represent a Grey Box Grassy Woodland ecosystem and includes:

• Tall trees
• Shrubs
• Native grasses
•  Riparian vegetation
• Aquatic plants

Together, these plant communities provide food, shelter, and breeding habitat for native wildlife while
increasing local biodiversity.

Education and Community Engagement
The Urrbrae Wetland serves as a valuable outdoor classroom, offering authentic learning opportunities for students of all ages across a wide range of subject areas. Urrbrae Agricultural High School manages the educational programs conducted at the site for students from across South Australia.

Community Open Days are held at the Urrbrae Wetland and are organised by the volunteer group the
Friends of the Urrbrae Wetland. The Friends also assist with vegetation management and some grounds
maintenance. This partnership is supported by the City of Mitcham Council’s volunteers program.

Benefits of the Urrbrae Wetland
Although it is a constructed wetland, the Urrbrae Wetland has been designed to function as a water
retention basin whilst having the benefits of natural wetland characteristics.
The Urrbrae Wetland has many positive impacts at a local, regional and national level:

Local Benefits

• Reduces the frequency of local flooding.
• Removes rubbish, sediments, pathogens, and pollutants from stormwater.
• Provides habitat for native plants and animals, increasing local biodiversity.
• Supports environmental education and community learning.

Regional Benefits

• Improves the quality of water entering Brownhill Creek, the Patawalonga Basin and Gulf St Vincent.
• Demonstrates sustainable stormwater management practices.
• Provides educational opportunities for schools and community groups across the region.

National Benefits

• Promotes water reuse and sustainable resource management.
• Demonstrates how urban wetlands can contribute to environmental sustainability across Australia.

Why Wetlands Matter
Wetlands are among the most productive ecosystems on Earth. They help control flooding, improve water quality, support biodiversity, and provide valuable recreational and educational opportunities. The Urrbrae Wetland demonstrates how a carefully designed urban wetland can replicate many of the ecological functions of a natural wetland while delivering significant environmental, social and economic benefits.

flora

Recreating 1836, the landscape surrounding the Urrbrae Wetland has been revegetated with a wide variety of native plants, all propagated from local species which would be found growing in a Grey Grassy Woodland habitat. This was done to recreate the area as it might have looked like prior to European Settlement in 1836. These plants play a key role in:

• Reducing water velocity
• Removing nutrients
• Oxygenating the water
• Providing food and shelter

Some of the species that have been planted to recreate the Grey Grassy Woodland habitat are:

Canopy

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Under Story

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Ground Cover

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Aquatic Zone

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