Study to provide Nati lake insight

Studies into modern catchment circumstances involving Natimuk Lake are set to provide insight into the potential of the lake to capture and regularly hold water.

Catchment leaders are also looking at landscapes influencing water flow and levels at west Wimmera’s Lake Wallace at Edenhope and St Marys Lake between Mitre and Tooan.

Natimuk Lake, for many years a popular recreation and waterfowl refuge, is dry.

The lake’s status and potential has been the subject of persistent community debate.

Wimmera Catchment Management Authority chief executive David Brennan said studies into lake catchment areas would help in understanding changing environmental circumstances.

He said he suspected results, particularly where catchment areas included broadacre-farming land, were likely to reflect significant changes in land use.

“For example, for many years we’ve seen a transition from grazing to crops and constantly improving cropping techniques based on a need, in a variable climate, to retain soil moisture,” he said.

“But how much of an impact is this having on water flow?”

“We expect the study work to be complete in a month. The information will provide us with a rational and factual understanding of water regimes at the lakes, based on climate and landscape conditions we’ve experienced in the past 20 or 30 years.

“In Natimuk Lake’s case, when we have this information we will have a good understanding of the probability of the lake receiving water under different rain scenarios and how we might be able to manage this into the future.

“But one of the take-home messages in all of this is that when you alter a catchment, some of the outcomes can be irreversible.”

Never say never

Mr Brennan said the authority had been working with the community to identify areas of Natimuk Lake catchment that might be restricting or diverting water away from the lake.

But he could not promise a time when the lake could justify artificial watering.

“We’re investigating all scenarios and trying to leave no stone unturned,” he said.

“One of these has involved exploring the impact of a weir structure.

“When it comes to getting water in the lake we never like to say never. But there are obvious costs associated with buying water and developing the infrastructure necessary to allow this to happen.

“Natimuk Lake, unfortunately, doesn’t have obvious characteristics that support a watering regime. What we know is that it is a large but relatively shallow lake that has always been prone to high evaporation levels. Any sort of watering would require in-depth cost analysis.

“What we first need to do is understand what has happened and is happening in the lake’s catchment. This of course also applies to our other study lakes as well.”

Natimuk, unlike many other historic recreation lakes in the Wimmera-mallee, is separate from the Wimmera River headworks and supply system.

It is instead part of an ancient Natimuk-douglas chain of lakes, a fresh and saline wetland system that is a remnant of a former massive prehistoric north-south waterway that ran from the Murray River to the sea.