A rare upland wetland that is one of only three of its kind in the entire Hawkesbury-Nepean System.
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Glenbrook Lagoon
Recent water quality testing at Glenbrook lagoon has revealed that the stormwater entering the Lagoon has very high levels of bacteria that may pose a risk to anyone who has contact with the water. Council is working together with Sydney Water to find the source of contamination and a solution to this problem.
Glenbrook Lagoon is a rare upland wetland that is one of only three of its kind in the entire Hawkesbury-Nepean System. The Lagoon provides habitat for flora and fauna species that are otherwise unusual in the area. For many years, large amounts of sediments and nutrients have been flowing into Glenbrook Lagoon from the surrounding residential areas. This has encouraged the growth of nuisance aquatic plants, which 'choke' the lagoon and make it unsuitable for the native aquatic plants and animals that would normally live there if conditions were better.
Two noxious aquatic weeds are of major concern on Glenbrook Lagoon; they are Salvinia molesta and Cabomba caroliniana. Both plants were introduced from the Americas and are now both listed in the top twenty Weeds of National Significance in Australia. Both are noxious weeds in NSW. They may have been introduced by individuals dumping unwanted aquarium plants into the lagoon. They multiply from fragments and can double the area they cover in a matter of weeks in summer. The Salvinia floats on the water surface forming a dense green mat of vegetation. The small white flowers of Cabomba can be seen just above the water surface of the lagoon. The stems can be over 2 metres long and under the water surface a 'forest' of Cabomba out-competes our native species for nutrients, light and space.
As the weeds complete their life cycle and die, organic matter accumulates on the bottom of the lagoon and is eventually broken down by microbes in the water. This process of decomposition removes oxygen from the water making it unliveable for many types of aquatic life.
Recommended Links:
- Cabomba Weed Management Guide: www.weeds.gov.au
- Salvinia Weed Management Guide: www.weeds.gov.au
- Blue Mountains Specific Information: www.bmcc.nsw.gov.au/sustainableliving/environmentalinformation/livingcatchments
- Glenbrook Lagoon Bushcare Group: www.weedsbluemountains.org.au/group_glenbrook_lagoon.asp
- Glenbrook Lagoon Restoration Project: www.bmcc.nsw.gov.au/sustainableliving/environmentalinformation/livingcatchments