2004/14 – 2020/22 Bermagui (New South Wales) – Turbidity, Iron

Bega Valley Shire Council issues boil-water notice from Brogo to Bermagui

11 Jan 22 (aboutregional.com.au)

The combination of heavy rainfall and summer visitors to southeast NSW has led to Bega Valley Shire Council issuing a boil-water notice for users connected to the Brogo-Bermagui water supply.

Boiling water before use for drinking, food preparation, teeth cleaning and ice-making is now considered essential for water users in Quaama, Cobargo, Bermagui, Beauty Point, Fairhaven, Wallaga Lake, Wallaga Lake Heights, Wallaga Lake Koori Village and Akolele.

Water issues are not new to Bega Valley communities, but they have been somewhat mitigated in recent times by the temporary water treatment facility in Brogo.

Bega Valley Shire Council’s water and sewer services manager, Chris Best, said the Brogo facility is struggling to manage the current increase in demand, and his team has been “working around the clock” since heavy rain on Thursday, 6 January, 2022.

“With more visitors in the area during the summer break, it has reached the point where the treatment plant can no longer cope with the higher demand,” he said.

“The temporary plant has reduced the need for boil-water notices since introducing flocculation technology, but even this has its limits which is why we are in the process of constructing a permanent treatment and filtration plant at the same site.”

Mr Best said that when the permanent facility is up and running – expected in late 2022 – the Brogo-Bermagui water supply will no longer require boiling after heavy rain events.

“We have previously avoided boil-water notices by carting water from our southern supply, however given the increase in usage at this time of year, this is currently not possible,” he said.

“Our water team will continue with a regular program of testing water from the Brogo River source, which is known for high turbidity levels, particularly following the Black Summer bushfires which heavily impacted the catchment.”

All other water supply in the Bega Valley Shire is currently unaffected.

Residents of bushfire-ravaged Bega Valley rely on carted water after flooding

18 Feb 2020

Water is being trucked to several NSW south coast towns and a mobile treatment plant is filtering water at the Brogo dam

Towns in the bushfire-ravaged Bega Valley are relying on water carted in milk tanks after flooding made the catchment’s water supply undrinkable.

Bega Valley shire council has been trucking bore water from Bega for towns such as Bermagui, Cobargo and Quaama and the Australian Defence Force has set up a mobile water treatment plant to filter the water supply at the Brogo dam.

The Brogo catchment was burnt out in disastrous fires in the first week of January.

With no trees, grasses or other vegetation to act as a buffer, sediment, ash and other organic debris washed into Brogo dam last week when more than 150mm of rain fell across the catchment.

Chris Best, the council’s manager for water and sewer services, said residents were now under level four water restrictions to try to avoid a notice to boil water.

“It’s just another thing they’re having to go through,” Best said.

Best said in addition to carting water in – which had cost $300,000 so far – and the ADF mobile treatment plant, the council was pumping water from a creek that it hadn’t used to supply the water system for 20 years.

He said in the immediate aftermath of the flooding, turbidity levels reached 600 NTU. They are still at 25 NTU and for drinking water that figure should be five or less.

The dam is still overflowing and 200 megalitres of water a day are pouring over the spillway into the Brogo River.

“This shire has a pristine landscape,” Best said. “[Until now] we’ve managed not to have water treatment ever, just chlorination.”

The council is now seeking financial assistance from the New South Wales government to build a temporary water treatment plant, which is expected to cost $300,000. The mayor, Kristy McBain, is talking to the state’s water minister, Melinda Pavey.

The NSW government has said it will provide financial assistance to the council up to $350,000 for emergency water carting until 10 March, or until normal supply is restored, whichever is the sooner.

A permanent plant was promised by the state government in 2018 but still has to be built.

Best estimated the catchment would “stay burnt out for 18-24 months, meaning every time it rains it will happen again”.

“How to get through the next two years is something we have to work out,” he said.

2004/14 – Bermagui (New South Wales) – Turbidity

From a total of 62 samples, 2 exceedances occurred from 1 Jan 2004 to 31 Mar 2014. The
highest exceedance of 8.8 NTU was recorded on 1 May 2012 at sample site 709 in
Bermagui. The other exceedance was 5.1 NTU on 16 Feb 2010 at sample site 719 in
Bermagui. Iron exceedances were also recorded in the samples.

Chlorine-resistant pathogen reduction: Where filtration alone is used as the water treatment
process to address identified risks from Cryptosporidium and Giardia, it is essential
that filtration is optimised and consequently the target for the turbidity of water leaving
individual filters should be less than 0.2 NTU, and should not exceed 0.5 NTU at any time
Disinfection: A turbidity of less than 1 NTU is desirable at the time of disinfection with
chlorine unless a higher value can be validated in a specific context.

Aesthetic: Based on aesthetic considerations, the turbidity should not exceed 5 NTU at the
consumer’s tap

2004/14 Bermagui (New South Wales) – Iron

From a total of 52 samples, there were 35 exceedances from 1 Jan 2004 to 31 Mar 2014.
The ADWG value for iron is based on aesthetic considerations is 0.3 mg/L. Iron has a taste
threshold of about 0.3 mg/L, gives the water a rust brown appearance and can cause
staining of laundry and plumbing fittings. This high number of exceedences suggests iron in
the distribution system is a persistent problem.

Based on aesthetic considerations (precipitation of iron from solution and taste),
the concentration of iron in drinking water should not exceed 0.3 mg/L.
No health-based guideline value has been set for iron.

Iron has a taste threshold of about 0.3 mg/L in water, and becomes objectionable above 3 mg/L. High iron concentrations give water an undesirable rust-brown appearance and can cause staining of laundry and plumbing fittings, fouling of ion-exchange softeners, and blockages in irrigation systems. Growths of iron bacteria, which concentrate iron, may cause taste and odour problems and lead to pipe restrictions, blockages and corrosion. ADWG 2011