Vasse water woes input
Habitat engineering techniques have been flagged by an expert as a potential solution for the water quality of the Lower Vasse River.
The nutrient and algae-rich river was again in the spotlight last Wednesday at a City of Busselton public access meeting.
Ozfish senior project manager Andrew Matthews suggested this week a solar-powered aeration device or biological islands could reduce nutrients in the river.
Both techniques have successfully been used in Perth’s Bibra Lake and Lake Joondalup. However, Mr Matthews conceded the complexity of issues at the river would make these solutions hard to maintain.
“I haven’t seen anything like this in WA,” Mr Matthews said.
“There is obviously a lot of community concern.”
He said measures undertaken on the river had not worked, and other methods needed to be tested.
FIA Technology Director Bernie Masters said he had suggested 'vegetated floating islands' to the river but the City of Busselton had refused his possible solution due to its expense.
“The problem with the Lower Vasse River is that it has taken some 160 years since European settlement of the Vasse area for nutrients to build up and cause poor water quality, with everyone wanting a quick fix that will work overnight and cost next to nothing,” he said.
“The reality is that it will take millions of dollars and several decades to overcome the nutrient enrichment problems of the river.”
The Lower Vasse River is the site of several challenging issues including the combination of a drying climate, a flat geography, and the competing use of agriculture and urbanisation.
Former chairwoman of the Vasse Taskforce, Vasse MLA Libby Mettam, said she would ask the State Government in Parliament what the overarching strategy was to restore the river.
She said the Vasse Taskforce had improved the response to crises in the river but had not addressed the complex management structure of different parts of the system.
“I believe there is an opportunity to introduce new thinking into our waterways management to bring about real improvement and change,” she said.
“Ultimately it would be beneficial if a single locally based and accessible agency managed all aspects of the system.”
A dry 2019 winter has resulted in lower water levels exposing sediment on the river bed but a Geocatch spokeswoman said the Department of Water and Environmental Regulation had tested the phytoplankton, and nutrient levels which were similar to previous years.
“Long-term improvements in the Lower Vasse River will require a combination of actions to reduce nutrients off the catchment and nutrients in the sediments,” she said.
“Dredging sections of the river may help improve the aesthetics of the river in some areas, however algal blooms will still occur due to the nutrients from the remaining sediments and other sources in ground and surface water.”
The City of Busselton is leading the Revitalising Geographe Waterways Program, working with State government agencies.
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