Study to pro­vide Nati lake in­sight

The Weekly Advertiser Horsham - - News -

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.

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