Lake Monger (Galup) Reserve Swale Refurbishment

It is a State Government project funded by the Department of Water and Environmental Regulation through the Greening Our Communities Small Grant Program, to improve the water quality of Lake Monger. 

The project aims to refurbish the nutrient stripping swales or steams on the east side of Lake Monger so they can effectively remove nutrients, sediment and pollutants from stormwater entering the lake. This will help reduce algal blooms in summer and improve the quality of water in the lake. Planting native species around the streams will also attract and support native wildlife to the lake.

The swales are channels on the east of the lake which receive stormwater from the freeway through several drains. The swales were originally shallow and planted densely with reeds. As water trickled slowly through the reeds they stripped sediment, nutrients and pollutants from stormwater before it entered the lake.

Over time the channels were deepened and the number of reeds has decreased, making them less effective. The project will reinstate the swale shape and native sedges to re-establish the nutrient stripping capacity which has been lost.

The project has five stages:

1. Removal of non-native species – mostly sheoaks.
2. Scraping sediment from the channels leading from each drain to remove accumulated nutrients and pollutants.
3. Reshaping of the channels to ensure slow movement of water along the channels and maximise the opportunity for nutrient stripping and sediment trapping.
4. Dense planting of the channels with sedges to slow water movement and enable nutrient uptake and sediment trapping.
5. Replanting of the fauna habitat zones with the right species – things like flooded gum and paperbarks which are compatible with sedge growth and support local fauna.

As Lake Monger is a registered Aboriginal Heritage Site, registered knowledge holders must be consulted regarding any proposed works at the lake. The Town has met with the knowledge holders who are supportive of the project. The Elders support works to improve the water quality of the lake, remove non-native species and plant native species which support the wildlife of the lake.

The Town is also required to obtain a clearing permit to remove vegetation around the edge of the lake. The Town will apply to Department of Water and Environmental Regulation for a clearing permit before removing any vegetation.

In 2002, a non-native variety of sheoak was planted along the edge of the channels. There are two problems with this particular species:

1. It takes over, preventing native species from growing. This reduces habitat for native animals;
2. It releases plant chemicals into the soil which suppress the growth of other plants. It inhibits the growth of sedges along the channels which are needed to help strip nutrients, sediment and pollutants from stormwater. It also prevents the growth of other native wetland species which provide valuable habitat for local wetland animals such as water birds, turtles and frogs.

The sheoak must be removed to revitalise the swales so they can function properly and to support local wetland species.

Around 500 – this sounds like a large number however many are immature saplings which have popped up from underground stems.

The tree removal and earthworks will most likely commence late January/early February. Summer is the best time to undertake these works when the water level is lowest in the channels.

Planting of sedges along the channels and native species in the fauna habitat zone will commence in May/June to coincide with winter rain.

The project will be completed when all planting has been undertaken. It is anticipated planting will be completed by the end of June.