2017/20 – Lake Burragorang (New South Wales) – Algae, Saxitoxins, Salinity, Fire, sediment etc

September 2020: Lake Burragorang – Algae

Biovolume of Dolichospermum sp. breached the minor incident threshold of 0.3 mm3/L. Potential toxin producing species. No toxins detected. Naturally occurring organism in
waterways. Sydney Water and NSW Health notified by email and in a meeting on 17th September as soon as the results were reported. Discussed supply configuration preferences with Sydney Water regarding balance of water quality risks.

September 2020: Lake Burragorang – Algae

Trace level of saxitoxin detected in Lake Burragoran. Detected at the surface, no impact on water supply for treatment.  Naturally occurring organism in waterways. NSW Health and Sydney Water notified. Additional sampling and toxin testing of supply depth initiated.
Subsequent samples showed a decline in potential toxin producing algae.

December 2020: Lake Burragorang – Algae

Potential toxin producing algal biovolume ~ 0.244 mm3 in surface composite at DWA2. Detected at the surface, no impact on water supply for treatment. Naturally occurring organism in
waterways. Update sent to stakeholders, drawing from lower outlet where less algae present.

January 2021: Lake Burragorang – Algae

Trace detection of saxitoxin analogues ~ 0.7 ug/L at offtake depth within the lake. Detection well below health guidelines, no impact on water supply for treatment at this level. Naturally occurring organism in waterways. Results & updates notified to Sydney Water and NSW Health. Total toxins below limit of detection and no toxin producing algal cells in offtake depth.

‘Concerning’: Sydney’s water catchment faces rising loss to mining, contaminants


August 20 2017

Coal mining in Sydney’s catchment is having a “cumulative and possibly accelerated” impact on water flows but its full effect is unknown because of a lack of monitoring.

These are among the findings of the 2016 Audit of the Sydney Water Drinking Catchment, a study required by law every three years, that the Berejiklian government quietly tabled in parliament this month. Just a single copy of the report was available to borrow.

The audit, which covers the 16,000-square-kilometre catchment that stretches from Lithgow in the Blue Mountains to near Cooma and stores as much as 2.6 million megalitres of water, found “reduced water availability” compared with the 2013 report.

It found mixed trends, with parts of the catchment improving but others worsening. Lake Burragorang – Sydney’s main reservoir sitting behind Warragamba Dam – was among areas with the poorest results for surface flows.

Water extraction by mining and other uses continue to increase, while wetlands appear to have deteriorated. There had also been “a significant increase” in areas affected by bushfire, the audit said.

“The audit found an emerging issue of unquantified loss of surface flows associated with the cumulative impacts of underground coal mining activities,” it said.

Peter Turner, mining projects science officer for the National Parks Association said the audit “paints a picture of a catchment under pressure and continuing to be damaged by coal mining”.

A spokesman for Energy Minister Don Harwin said the audit showed the city’s drinking water “has the highest possible quality rating in the world” and it was a top priority to maintain the standard.”[T]he government is looking closely at the independent audit and will ensure that whatever actions are required to protect our catchment are taken,” he said.

Awkward timing

The audit’s release comes at an awkward time for the government. The Supreme Court this month ruled invalid the approval for the extension of the Springvale coal mine because the mine pumps untreated waste into the Coxs River that flows into Lake Burragorang, accounting for about 80 per cent of Sydney’s water.

Springvale, though, is the sole supplier to the Mt Piper power station, which generates about one-sixth of NSW electricity. The government may need special legislation to nullify the Supreme Court’s decision and concerns about mining in the catchment raised by the audit may complicate its case.

Stuart Khan, an associate Professor in the School of Civil & Environmental Engineering at the University of NSW, said the trends revealed for Lake Burragorang were “very concerning”.

Electrical conductivity– which gauges how salty the water is – had been worsening in the lake for the past two decades, as had other water-quality parameters such as nitrogen and dissolved oxygen.

Rising nitrogen and falling dissolved oxygen levels would traditionally have been associated with sewage issues but, as the audit notes, plant upgrades had significantly reduced the burden from this source.

“Worsening salinity at a time when the lake is full points to long-term catchment decline,” Professor Khan said. “This means that the salt and nitrogen contamination reflects increasing emissions from other sources such as mining and agriculture.”

Sydney’s catchment suffered a major cyanobacterial bloom in 2007. “By allowing nitrogen concentrations to gradually increase, we are setting ourselves up for the risk of more large-scale bloom events in the future,” he said, adding more science “is urgently required” to understand the sources and develop effective controls.

‘Puzzling’ omission

As with previous audits, this report highlighted “inadequate” data and monitoring. Key datasets, such as those tracking native vegetation, had not been updated since 2013, it noted.

“The audit records the potential for mining to cause significant and serious groundwater loss” in the special areas that are intended to protect the core of the catchments for the reservoirs that supply Greater Sydney and the Illawarra, Dr Turner said.

“It does not, however, record that the available evidence strongly indicates that this is already happening.” (See detailed NPA comments on the audit here.)

That omission is “puzzling” since company reports already indicate some 29 to 40 million litres of water a day are entering mines in and around the Metropolitan and Woronora Special Areas, Dr Turner said.

“This corresponds to 10,585 to 14,600 million litres of water a year,” Dr Turner said. “This is a disturbingly large volume and is as much or more than some of the licence-restricted water extractions permitted in sub-catchments outside the special areas.”

The water inflows to the underground mines are caused by subsidence after the fossil fuel is extracted, leading to fissures that can divert water from aquifers or from surface rivers and swamplands.

“Mine inflows can’t be turned off with a tap,” Dr Turner said. “They continue until there’s no more water or until the mine fills and leaks its contaminated water.”

Even research, it seems, falls through the cracks.

Research recommended in the 2010 audit into the connectivity of surface and ground water that had been identified as underway three years later couldn’t be found.

“[N]o published results could be located either in the public domain or through communications with key personnel within DPI Water and WaterNSW,” the 2016 report said.

Surface water loss can also dry out endangered swampland, adding to the bushfire risks, the audit said.

“Such losses could be significant in dry and drought conditions,” it said. “The loss of surface water can also impact on bushfire severity, and thus the condition of upland swamps and their flora and fauna communities.”


Coal mining in the Schedule 1 Special Areas itself “makes nonsense of the legislated intent” of the protected areas, Dr Turner said, noting that water extraction is not permitted in the nationals parks that border the Metropolitan and Woronora regions.

“The National Parks are protected from water loss, but not the Special Areas, which are in effect Sydney’s most important public health asset, he said. Those areas are also high
conservation regions and “contain some of the few remaining areas of pristine bush in NSW”.

Greens NSW environment spokeswoman Mehreen Faruqi said it was “simply irresponsible” to continue to allow longwall coal mining in Sydney’s catchment.

“Streams nearby these mines have gone from gaining groundwater to now losing it, which is having significant impacts on their flows and environmental outcomes for wetlands,” Dr Faruqi said.

“It’s pretty disappointing that this audit was tabled with no explanation or notification to stakeholders. Surely issues such as drinking water which impacts everyone deserve more transparency,” she said

The next focus on water may come if the government attempts to pass legislation aimed at nullifying the Supreme Court’s decision on Springvale mine.

“The [State Environmental Planning Policy] was put in place for public health reasons, to ensure that the water supplied to the communities of Sydney and surrounds is safe,” Ms Higginson said.

“It would be hard to envisage a basis upon which a government would reverse standards and policies that were put in place for this reason.”

The track record of governments acting on the audits’ recommendations, such as for better monitoring, hasn’t been good, Dr Turner said.

“It’s very disappointing that the audit has to repeat or echo recommendations that have been made to the government, without evident effect or action, in reports its commissioned over at least the past decade, such as the 2014 NSW Chief Scientist’s report on catchment impacts and the 2007 report by Evans and McNally,” he said.

‘Shocking’: NSW government cops audit scolding over catchment inaction


July 1 2018

The Berejiklian government ignored warnings by an auditor for two years that it in needed to address rising salinity at Sydney’s main reservoir, a delay the Labor opposition describes as “frankly shocking”.

As Fairfax Media reported last year,  the triennial audit of Sydney’s water drinking catchment found salinity levels at Lake Burragorang had risen over a 20-year trend, and were twice the level of other catchments. Coal mining, a key source of those salts, was having a “cumulative and possibly accelerated” impact.

However, a report into pollution of the catchment, released by the Auditor-General last week, said despite the 2016 audit’s call for an investigation into the source and implication of the salinity in the basin behind Warragamba Dam, nothing had been done.

Of the three public authorities now responsible for water quality at Lake Burragorang, the Auditor-General recommended the NSW Environment Protection Authority review the impact of licensed activities on water quality and develop strategies to improve water quality by June 30, 2019.

The other two agencies are the Department of Planning and the Environment and WaterNSW.

NSW Environment Minister Gabrielle Upton said in a statement: “The EPA is the state’s lead protector of the environment and the Minister supports any findings that result in a better outcome.”

“The EPA has considered the Auditor-General’s report, has responded to all the findings and is in the process of implementing many of the recommendations.”

Chris Minns, Labor’s water spokesman, said government agencies had been bickering over taking responsibility “and we are still none the wiser as to who is responsible for this mess”.

“It is frankly shocking that the NSW government refused to lift a finger for two years after being warned about potential threats to Sydney’s primary water source.”

Justin Field, the Greens urban water spokesman, said the lack of an agency response to deteriorating water quality showed the government was “putting coal ahead of community health”.

“The increasing salinity in our major water supply will increase the cost of water treatment and that cost is being shifted from mine operators to the bills of Sydney resident,” he said. “That cost needs to be put back on the mines and no new mining approvals should be granted in the catchment.”

‘Serially ignored’

Peter Turner, the mining projects science officer at the National Parks Association, said concerns about the impacts of mining on water date back to at least the 2014 report of the NSW Chief Scientist.

“Successive governments have been repeatedly warned in various reports over more than a decade of the increasingly adverse impacts of mining on Sydney’s drinking water catchment,” Dr Turner said.

“No matter ministerial assurances of careful consideration, these reports and their recommendations have been serially ignored or shelved,” he said, adding that there was no reason to expect the soon-to-be released advice from the expert panel “would fare any better”.

While Lake Burragorang got most of the attention in the Auditor-General’s report, other mining-impacted reservoirs that supply southern Sydney, Wollongong and the Illawarra had been left “in the shadows”, Dr Turner said.

For its part, WaterNSW said reducing salinity at the catchment storages was consistent with its water-quality objectives.

“However, salinity levels are not problematic and do not currently impact on WaterNSW’s ability to meet water-quality guidelines,” an agency spokesman said.

Other EPA issues

While recommending the EPA take responsibility for addressing the issues at Lake Burragorang, the Auditor-General found the authority had a range of other shortcomings.

For instance, the report determined the EPA had “unreliable detection practices, and weaknesses in its governance approach, [limiting] its effectiveness to consistently apply regulatory action”.

As a result of its ineffective detection, “there is a risk that the EPA may not be applying regulatory actions for many breaches and non-compliances”, it said.

“The risk-based framework and over-reliance on self-reporting leaves our environment and in particular our drinking water vulnerable to pollution incidents that go unnoticed or are inadequately prosecuted and cleaned up,” Mr Field said.

Bushfires threaten Sydney’s drinking water supply


Dec 27 2019

Firefighters are working to contain the spread of fires that have burnt everything but a “small portion” of land surrounding Sydney’s major water catchment ahead of another heatwave next week.

On Boxing Day, more than 1400 firefighters took advantage of milder conditions by back-burning to slow the spread of the 70 fires still burning across the state.

Conditions are set to deteriorate over the weekend with temperatures forecast to soar to the mid-40s in parts of western Sydney by Tuesday.

The fire preparation comes as an analysis showed more than half a million people in NSW are exposed to a high or extreme risk of bushfire.

Water bureaucrats have also been working “around the clock” to protect water supply assets from flames that came within kilometres of drought-depleted dams.

The Green Wattle Creek and Ruined Castle fires surrounding Lake Burragorang, which supplies about 80 per cent of Sydney’s water through Warragamba Dam, have burnt more than 223,000 hectares, nearly doubling in size in the past fortnight.

In early December, Rural Fire Service firefighters conducted strategic backburns around Warragamba as the Green Wattle Fire took hold on the eastern side of Lake Burragorang.

The lake and dam have now been almost completely encircled by bushfire, with only a “small portion” on the northern side of the lake currently untouched by fire, RFS spokesman Ben Shepherd said.

The impact of the spread of fires in the past two weeks affecting the Warragamba catchment had been “really extreme”, said Professor Stuart Khan, a professor of civil and environmental engineering at the University of NSW.

“The majority of the perimeter of Lake Burragorang has been impacted, and Wollondilly and Coxs rivers, with significant quantities of ash flowing,” he said.

There were two risks to water supply, said Professor Khan, an expert on water contamination. The first was that fire would destroy pumping stations and damage pipes, which so far hadn’t happened, and the second was threat of a large downpour causing ash to run off and pollute the water supply.

Even before the fires, the lack of rain had meant organic material which could pollute water had been building up in greater concentrations.  From previous experience and modelling, he said if there was a big downpour –  in excess of 100mm to 200mm of rain, causing run off for the first time in two years – that could cause serious problems.

WaterNSW has since deployed floating booms and curtains across the Warragamba catchment to serve as a barrier to block ash from filtering into the untreated part of the water supply, while water quality scientists are monitoring the dam using sophisticated, real-time technology.

“The current priority is to protect against ash or debris being washed into the storage following a rain event,” the WaterNSW spokesman said.

Water Minister Melinda Pavey said the NSW water agencies had been “working around the clock to ensure that our towns have access to water.”

“Our assets across the state remain intact and are still supplying water to towns affected by these severe fires,” Ms Pavey said.

But Professor Khan said the combination of fires and drought had pushed water managers “out of their experience and comfort zone”.

A spokesman for WaterNSW said the fact there had been no significant damage to assets in the Blue Mountains and Warragamba Dam areas was a testament to the firefighting efforts of the RFS.

Bureau of Meteorology forecaster Jiwon Park said while there have been benign conditions over Christmas, a heatwave will bring temperatures in the 40s to parts of Sydney over the weekend before a southerly change hits the state early next week.

“Ahead of the southerly the temperatures will be rising,” he said.

Bureau of Meteorology duty forecaster Rose Barr told AAP some areas were forecast to reach “extreme heatwave conditions”.

“With the increasing heat and winds, the fire danger will worsen into the new week, with Monday and Tuesday most likely to be the most significant fire weather days,” she said.

Daily maximum temperatures in Penrith and Richmond are forecast to steadily climb to a high of 43 degrees by Tuesday, while Parramatta is forecast to reach 41 degrees that day.