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Point Sturt and Districts Landcare Group Inc: Angas River

Point Sturt and Districts Landcare Group Inc: Angas River

Bottle number: 110

About the water

Point Sturt and Districts Landcare member Chris Bagley taking a water sample from Angas River.
Chris Bagley, Point Sturt and Districts Landcare member Chris Bagley.

Collected at: Beneath the bridge over the Angas River near Lake Alexandrina, South Australia

E: 318374, N: 6081210, Zone 54

View location on Google map

 

Collected by: Point Sturt and Districts Landcare Group Inc.

The Angas River is outside the Landcare Group district but the Landcare Group (and indeed all locals) are deeply concerned with the current state of the Angas River and of Lakes Alexandrina and Albert which should be a national disaster area.

 

Water quality:

Turbidity: NTU ~ 40
pH: 8.0
Nitrates: less than 0.5mg/L
Salinity: 6060┬ÁS/cm
Phosphates: 0.05mg/L
Dissolved oxygen: 5.5mg/L

The Angas River had stopped flowing some months ago and it is now not connected to Lake Alexandrina, so the pool of water from which the water sample was taken is a static pool (at this time).

ACT Waterwatch says:

The samples from Bottle 110 and Bottle 111 (like others in this batch) reflect the upper estuarine nature of Milang and the mouth of the Angas as the many years of low flows and saline ground-water input have quietly affected the system. I'm sure the Angas in Strathalbyn is quite high in pH, but relatively low in electrical conductivity and much of that coming from the limestone and phyllite in the catchment at the top of the Mt Barker part of the Mount Lofty Ranges. If, as the sample indicates, flow in the mouth of the Angas is tidal, then the salinity is equivalent to that of Lake Alexandrina, which has become steadily more saline in recent years. This is a product of the combined effects of low flows in both the Murray and the Darling, saline seepage in the ground water of the lower Murray from at least Murray Bridge and backflow mixing from the Coorong as the Murray Mouth/ Younghusband Peninsula has been closed more often than not for at least ten years. The water is probably salty to taste and not wonderful on the citrus but ...

The turbidity reflects the level of suspended material that comes from both the lake bottom sediments, which are marl-like, and the coloured sediments of the lower Murray (and Angas) catchment. The moderately high phosphate load may be an indication of prolonged agricultural use of the flood plains. Lake Alexandrina has had cyanobacterial blooms in the recent past, and supports plenty of biological activity.


Stephen Skinner
Molonglo Waterwatch Coordinator

About the site

Chris Bagley (with dog Bede) taking sample from beneath the bridge over the Angas River near Lake Alexandrina, South Australia. Photo: Bruce Allnutt.
Chris Bagley (with dog Bede) taking sample from beneath the bridge over the Angas River near Lake Alexandrina, South Australia. Photo: Bruce Allnutt.

Mouth of Angas River, where it empties into Lake Alexandrina.

Water has been removed from river at an increasing rate since approx 1970s: irrigation for vineyards and pastures, and small private dams for new homes in Hills catchments.

Nil or minimal flows at Mouth, approx 2003 to 2008. Significant flows September to October, 2009, after good local rainfall.

Major dredging of lake bed in 2007 to extend water pumping from Lake Alexandrina included deposit of spoil adjacent to Pygmy Perch breeding site, sixty metres downstream of sample site. Breeding ground was destroyed.

Lake Alexandrina was maintained at between 0.75 AHD and 0.85 AHD since completion of Goolwa Barrages in 1940s. At time of sampling it had fallen to (minus) -0.8 AHD and shoreline had retreated about 50 - 100m.

What's going on:

The Angas River is outside the Landcare Group district but the Landcare Group (and indeed all locals) are deeply concerned with the current state of the Angas River and of Lakes Alexandrina and Albert which should be a national disaster area.

Monitoring of water levels, salinity and ph levels.