Sanctuary Lakes: ‘Underwater mower’ to tackle lake

Sanctuary Lakes residents may spot an unusual boat in the area’s lake in coming weeks as the estate begins harvesting sea grass for a trial at Melbourne Zoo.

Each year, about 1200 tonnes of sea grass is removed from the saltwater lake and taken to the Wests Road landfill.

Sanctuary Lakes Resort general manager Tony Ferreri said disposing of the grass at the tip was costing residents about $100,000 a year.

So the resort splashed out $320,000 to buy a special sea grass harvester, a sort of underwater lawn mower.

It collects the grass and improves the quality of the water in the 60-hectare lake by keeping the grass at the desired height.

Mr Ferreri said the trial at Melbourne Zoo involved combining the sea grass with other waste to create compost for gardens.

Some of the sea grass will also be taken to a small Geelong-based manufacturer of garden fertiliser.

“Chemicals and pollution from upstream, combined with hot water, can stimulate rapid growth of the sea grass and the formation of algal blooms,” Mr Ferreri said.

“The lake requires a constant program of underwater mowing and collection, together with monthly monitoring of water samples.

“A healthy amount of sea grass assists with absorption of nutrients in the water, which reduces the severity of algal bloom.”