Patawalonga Lake system
The Patawalonga Lake is a man-made system that is 1.6 kilometres long and runs parallel to the coastline from Glenelg to West Beach. It is designed to stop flooding of urban areas by diverting storm water, and is kept clean and healthy by tides flushing the lake with seawater. It also provides an area for water sports and aquatic life.
The Patawalonga Lake system is a fully automated system. It includes the Glenelg Barrage, Northern diversion weir, Barcoo duct entrance and safety grille, South Lake, North Lake, Diversion basin, Patawalonga Creek and collection pond, Sturt River debris and sediment retention basin and the West Beach beacon, as can be seen from the overview map. Occasionally the system is operated manually to facilitate maintenance work in and around the lake and to lessen the impact of exceptional storm water flows and high tide events.
What's happening at Patawalonga?
There are currently two projects underway to improve the system's efficiency and safety.
1. Sediment management project
Sediment in the Patawalonga Lake system needs to be managed to maintain water quality and the general aesthetics of the lake. Sediment from the lake entering the Gulf St Vincent can also pose a threat to seagrass health. However, handling and disposal of sediment is difficult. It contains a high proportion of organic matter which takes years to dry out, and may contain metals and other chemicals in concentrations which restrain reuse and disposal options.
The sediment management project is a long-term approach to managing sediment in the system. It involves contract services and infrastructure so that the sediment quantity can be monitored and accumulated sediment can be removed. It also involves trials to find improvements and innovations in how sediment can be most cost effectively managed.
In 2008 a large amount of sediment was removed from the system near Tapleys Hill Road. And in 2014 approximately 25,000 cubic meters were removed and disposed of.
Between February and June 2015 there will be a program to remove and dispose of remnant sediment from the basins at the north end of the lake. This will involve:
- dredging sediment from the basins
- pumping it to the disused triangle of land between the Old and New Tapleys Hill Road alignments
- removing liquid from the sediment using geo-textile bag filtration
- transporting the sediment by truck for reuse off site in accordance with Environment Protection Authority guidelines.
This process was successfully used last year with minimal noise and odour impacts and no significant inconvenience to local communities.
2. Glenelg gates upgrade project
The Glenelg gates are at the mouth of the Patawalonga Lake. Built in the 1950s and 1970s, they provide important services by stopping flooding from sea storm surges and storm water flood flows, and allowing sea water to be circulated through the Patawalonga Lake to sustain its aesthetics and health. They also provide a walkway connecting Glenelg and Glenelg North across the mouth of the lake.
This project involves repairs and improvements to the operating system of the Glenelg gates and the replacement of the public walkway which is now complete.
Will the projects impact the community?
The sediment management project is expected to have little impact on the local community.
View a community update on the gates and an update on both projects, presented in March 2014 to the Patawalonga Watch Group.
Who manages the Patawalonga Lake system?
The Department of Environment, Water and Natural Resources facilitates the governance structure that manages the system, with support provided by the:
- Patawalonga Advisory Group that has met biannually since 2004 to provide strategic advice on the management of the system and as a forum to address issues associated with its operation. Representatives include the department, Adelaide Airport, Adelaide and Mount Lofty Ranges Natural Resources Management Board, Biosecurity SA, City of Holdfast Bay, City of West Torrens, Environment Protection Authority SA, SA Water and State Emergency Service SA.
- Patawalonga Watch Group that conducts audit and watchdog exercises each year. Representatives include the department, Adelaide Sailing Club, Adelaide Shores, City of Holdfast Bay, City of West Torrens, Glenelg Marina, Glenelg Residents Association, State Emergency Service SA and SA Police.
Patawalonga Lake emergency response contacts
Life threatening: 000 (all hours)
Flood events: 132 500 (all hours)
Environmental: (08) 8204 2004 (all hours)
General Patawalonga Lake contact
If you have any questions or issues regarding the management of the Patawalonga Lake please contact Asset Services Officer, DEWNR on (08) 8463 3675.