2016 Audit of the Sydney Drinking Water Catchment results for Wingecarribee

The 2016 Audit of the Sydney Drinking Water Catchment found the section river was in the top four areas that had the poorest water quality during the audit period.

The report, tabled in state parliament earlier this year, contained data from the Sydney catchment area between July 1, 2013 and June 30, 2016.

A council spokesman said this information was concerning and would be raised with Water NSW at the next quarterly meeting.

“The section of the report refers to a section of Wingecarribee River flowing into Wingecarribee Dam and the Wingecarribee Dam is managed by Water NSW.”

The audit said the Wingecarribee sub-catchment continued to be impacted by high nutrient loads associated with dairy effluent and ongoing adverse impacts from an incident in 1998.

It was the eighth catchment audit since 1999.

The council spokesman said council worked hard to ensure all drinking water meets the Australian Drinking Water guidelines for potable water.

“The report refers to raw water quality and not drinking water.

“Raw water is further treated by council to meet the Drinking Water Guidelines as approved by NSW Health. Council continues to work with WaterNSW in understanding the results and significant actions to continue to improve water quality in the Wingecarribee Catchment.”

The management of drinking water quality across the catchment follows a multi-barrier approach which is consistent with the Australian Drinking Water Guidelines 2011.

Another concerning finding to come from the audit was the perfromance of Wingecarribee’s sewage treatment plants (STPs).

Wingecarribee River sub-catchment was one of the locations auditors found STPs continued to experience poor water quality, despite the plants operating within licence conditions.

The Wingecarribee LGA also experienced the largest number of sewage system overflow incidents of all LGAs within the audit period.

The council spokesman said overflows most often occurred during wet weather events where high levels of stormwater and groundwater enter the sewerage system- such as the 2016 East Coast Low.

“Council has recognised the issues regarding wet weather impacts and has been working closely with the EPA to develop ongoing assessments and programs to reduce the impact of wet weather events on its treatment plants.

“Council provided Water NSW with data on reportable overflows. These overflows are routinely reported and STP’s are operating within licence levels.”

The report recommended priority be given to upgrading Bowral, Moss Vale and Mittagong STPs.

Council is currently reviewing options for potential upgrades to the three sewage treatment plants.

The Delivery Program 2017-2021 document outlines councils plans to spend $63,249,000 on the shire’s sewerage network over the next four years which will include upgrades to the Bowral and Moss Vale STPs.

One positive to come from the report was a decrease in the level of phosphorus loads at the Bundanoon (29 per cent) and Bowral (13 per cent) STPs compared to the previous audit period 2010-2013.

But there was a 139 per cent increase (from 380kg/year to 910kg/year) at the Moss Vale STP during the current period.

The report said this was due to population growth and limited capacity of the STP.

However the council spokesman said the Moss Vale STP was still lower than other STPs despite the increase and continued to comply with EPA licence requirements.

He agreed with the report’s findings the increase was a result of the town’s population growth.

“The capacity of the STP is being addressed through planning upgrades, most particularly a planned $25.5 million upgrade over the next three years.”

Moss Vale, Bowral, Mittagong and Bundanoon STPs all recorded a decrease in the nitrogen loads for the current audit period.

Another issue raised in the report was cyanobacteria.

According to Water NSW data used to compile the report, Wingecarribee Reservoir had the poorest cyanobacteria data.

Fitzroy Falls Reservoir triggered the largest number of cyanobacteria alerts in two years of the current audit period- 33 weeks in 2013-14 and 38 weeks in 2014-15.

It also triggered the third highest number of weeks on cyanobacteria alert in 2015-2016 (29 weeks).

The Wingecarribee River at Berrima was the most consistently problematic site in the catchment for cyanobacteria according to the report.

“Both the Fitzroy Falls and Wingecarribee Reservoir are managed by Water NSW,” the council spokesman said.

“Council has been made aware of increases in cyanobacteria at Wingecarribee Reservoir over the last twelve months and has operational protocols in place to manage the impacts of algae notifications.

“Council will however raise the need for more management practices with Water NSW at the next quarterly meeting.”

Nattai sub-river catchment was also one of the worst areas where downstream water quality was affected as a result of continued overgrazing and uncontrolled stock access to riparian zones.

The audit report also noted community efforts in areas including the Wingecarribee to regenerate and rehabilitate wetland areas.

The spokesman said these efforts would have a beneficial impact on the catchment and supported the work of Mittagong Creek Rivercare.