Wildlife boom as water settles

Wimmera catchment managers have predicted a boom in spring wildlife activity at the mouth of Lake Hindmarsh near Jeparit in response to water settling in the lake.

They have noted the spill of water from the Wimmera River, the result of winter rain in the region’s upper catchment, is already generating a considerable environmental response.

The expansive terminal lake, which has collected water only periodically in the past 20 years, is holding a ‘pool’ of about 12,000 megalitres of water.

The natural lake can hold as much as 430,000 megalitres and on the rare occasions it fills, directs water into Outlet Creek towards Lake Albacutya.

Wimmera Catchment Management Authority chief executive David Brennan said despite relatively dry weather across much of the region in the past fortnight, water was continuing to find its way from the river to the lake.

“There’s only a trickle going into the lake at the moment, but the good news is that we had rain in the upper or southern areas of the catchment only a week or so ago when other parts of the region missed out – in some places up to 20 to 25 millimetres – and that was enough to keep the upper system flows ticking along,” he said.

“Fingers crossed again that we get some more spring rain.”

Mr Brennan said the onset of warmer weather, combined with water, provided natural environmental triggers.

“It won’t be long until we start to see movement with a lot of water birds at Lake Hindmarsh, particularly duck species,” he said.

“That’s the type of response we’re expecting, considering there are plenty of early indicators such as people hearing a lot more frogs.

“These indicators, which represent an increase in aquatic life, tell us the eco-system is responding and rebuilding itself.”

The lower Wimmera catchment and waterways in the northern Wimmera provide a snapshot of the stark boom-and-bust contrasts underpinning environmental life in the region.

Little more than a decade ago, during the millennium drought and before 2011 floods, the lower-catchment of the Wimmera River near Jeparit was capturing international scientific attention.

The river in places had transformed from a typical oxygenated inland waterway that supported freshwater eco-systems into non-oxygenated and concentrated saline environments.

Stretches of the river at the time were regularly changing colour, causing considerable riparian dieback and evolving into anaerobic systems that supported limited, if any, recognisable life.

Environmental discharges in the Wimmera River, sourced from water-sharing allocations outside natural flows, are designed to mitigate circumstances that lead to a return to similar circumstances.

The 2011 floods helped restore environmental balance in the river’s lower reaches but fell short of filling Hindmarsh.