Environmental watering in southern Victoria

Stories on various environmental flows in southern Victoria.

Thomson and Macalister

The West Gippsland Catchment Management Authority is working with the Victorian Environmental Water Holder, Southern Rural Water and Melbourne Water to coordinate flow releases in the Thomson and Macalister rivers.

Flow peaks of up to 800 ML a day over four days will be experienced in the Thomson River on April 26 and May 11.  Flow peaks of up to 350 ML a day across seven days will be experienced in the Macalister River downstream of Lake Glenmaggie on April 27.

These releases are expected to enhance breeding opportunities for native fish populations, particularly the Australian grayling.

Similar releases over the past few years, combined with good rainfall, are helping improve the number of Australian grayling in the Thomson and Macalister Rivers following significant decline during the recent drought.

The WGCMA, together with the Arthur Rylah Institute for Environmental Research (ARI), have been undertaking annual fish monitoring in the Thomson and Macalister Rivers since 2005. This year a greater number of both adult and juvenile Australian grayling have been found in these systems.

WGCMA Chief Executive Officer Martin Fuller explained that the monitoring program aimed to ensure the appropriate use of environmental water by measuring against the achievement of ecological objectives.

 "One of our greatest priorities is the provision of spawning events for Australian grayling. This year we will be tracking the movements of a number of adult grayling to provide tangible evidence on fish responses to environmental flow releases," said Mr Fuller.

Moorabool flows

Another 380 million litres of water will be released into the Moorabool River to boost water quality for fish and platypus.

The environmental release will be Corangamite CMA's third since summer, with benefits provided for the River Blackfish, Australian Grayling and Platypus.

The release beginning on April 27 is on top of Barwon Water's current release and will take the combined additional flow up to 31 million litres a day at Morrisons – the water equivalent to 12.5 Olympic-sized swimming pools.

Platypus are considered widespread in the Moorabool River between Lal Lal Reservoir and Batesford, and the increased flows are likely to increase the presence of aquatic insects, fresh water shrimps, worms and yabbies for them to feed on.

"Juvenile platypus will start dispersing in autumn so it is important to maintain good flows in the river to connect habitat pools and facilitate the movement of platypus into new areas," Corangamite CMA River Health Executive Manager Trent Wallis said.

The rise in water level will flush organic matter such as leaves and bugs into the river, increasing nutrients and food sources for water bugs and fish.

It will also help flush sediment that has built up behind weirs and freshen water quality in habitat pools, with the majority of flows expected to make it to Batesford.