2011 + 2022 – Merimbula (New South Wales) – Copper, Turbidity

Clearer water trickles into Merimbula after council changes source to Tantawangalo Weir

7 May 2022: https://aboutregional.com.au/clearer-water-trickles-into-merimbula-after-council-changes-source-to-tantawangalo-weir/

Merimbula residents should have noticed clearer water running through their taps thanks to council switching to supplies from Tantawangalo.

Bega Valley Shire Council ditched water from Yellow Pinch Dam in favour of Tantawangalo Weir after months of heavy rain washed fine clay silt into the area’s main water store.

Water and sewerage services manager Chris Best said it resulted in an immediate improvement in water quality.

“With all the rain we’ve had this year, several catchments were affected by runoff, increasing sedimentation in our dams,” he said.

“So we are now sourcing water from places with a constantly-running supply.

“River sources like Tantawangalo can flush sediment through, resulting in a supply that clears sooner following heavy rain.”

He said while Yellow Pinch water is safe to drink, its brown appearance meant it was not something everyone wanted to use.

“It’s important to note the Tantawangalo supply – like any river – is still prone to sediment following heavy rain, but it will clear itself much sooner than the Yellow Pinch Dam,” Mr Best said.

“A permanent solution rests with adding filtration to our water treatment facilities and this is coming, with a new Yellow Pinch treatment and filtration plant scheduled for delivery in 2027.”

He said filtration had been introduced to Bemboka’s water supply in 2019, filtration and treatment were nearing delivery for the Brogo-Bermagui supply and construction of a new plant was about to start in Bega.

Merimbula (New South Wales) – Copper

From a total of 246 samples, 2 exceedances occurred from 1 Jan 2004 to 31 Mar 2014. The
highest copper exceedance was 2.59 mg/L at sample site 312 in Merimbula on 1 Aug 2011. The
ADWG guideline limit for copper is 2 mg/L for health considerations and 1 mg/L for aesthetic
considerations. The taste threshold for copper is in the range of 1‐5 mg/L and at concentrations
above 1 mg/L copper can cause staining on sanitary ware. Evidence of this has been recorded for the system, particularly in Merimbula and Tura Beach.

Based on health considerations, the concentration of copper in drinking water should not
exceed 2 mg/L.
Based on aesthetic considerations, the concentration of copper in drinking water should
not exceed 1 mg/L.

Copper is widely distributed in rocks and soils as carbonate and sulfide minerals.

Copper is relatively resistant to corrosion and is used in domestic water supply pipes and fittings. It is also used in the electroplating and chemical industries, and in many household goods. Copper sulfate is used extensively to control the growth of algae in water storages.

Copper is present in uncontaminated surface waters at very low concentrations, usually less than 0.01 mg/L. The concentration can rise substantially when water with a low pH and hardness remains in stagnant contact with copper pipes and fittings. Under these conditions, the concentration of copper can reach 5 mg/L or higher. In one extreme case overseas, a concentration of 22 mg/L was reported.