Hunter Water's production of recycled water has dropped by 13.6 per cent compared to five years ago, a figure critics have seized upon to argue for a greater investment in water conservation initiatives in the Lower Hunter.
Data from the Bureau of Meteorology's National Performance Report on urban water utilities shows Hunter Water supplied 4651 megalitres of recycled water in 2019-20.
But prior to that the water utility recorded three consecutive years of falling recycled water output - it produced 5384 megalitres in 2016-17, 4923 in 2017-18 and 3862 in 2018-19.
The Healthy Hunter Rivers Group, which is fighting to stop the construction of new Hunter dams, argue the statistics prove more needs to be done in the area of water conservation and efficiency rather than investing in a new dam.
Dams are among a range of options, including increased recycling and desalination, that Hunter Water is presently investigating as part of a review of the Lower Hunter Water Security Plan.
Upper Chichester Group spokesman Allan Rumble said dams should not be included as an option to improve water security.
"There is already an over-reliance on dams with around 94 per cent of water coming from the Williams River catchment. The environmental, social and economic impacts of building a dam have already been proven to be disastrous in the Williams River catchment.
"Healthy Hunter Rivers group now demands that Hunter Water drop their lust for dam building as an option for water security in the Lower Hunter.
"Dams are dinosaur technology with regards to water security. The people of the Lower Hunter want a diverse range of water options for the future with a priority in demand management, recycling/reuse and stormwater harvesting. Not a greenhouse gas emitting dinosaur with ongoing sustainability issues."
A Hunter Water spokesman said the organisation was committed to investing in new recycled water projects and initiatives to reduce network leakage and water consumption.
This includes a $6 million investment between 2020 and 2024 on recycled water schemes for public parks, playing fields and open spaces.
A further $32 million will be invested on water loss improvement initiatives to reduce leakage within the water network.
"Hunter Water transparently shares its performance statistics, including via our annual report, our annual Compliance and Performance Report and accompanying Water Conservation Report as well as the Commonwealth Government's annual National Performance Report," a spokesman said.
"A number of the metrics quoted in the Healthy Hunter Rivers statement misrepresent the published data, do not recognise methodological changes between reporting years, and rely on statistics that are now more than 18 months old."
The Healthy Hunter Rivers Group also seized on statistics that showed a spike in the Hunter Water's greenhouse gas emissions.
The National Performance Report shows Hunter Water's total net greenhouse gas emissions went from 163 net tonnes of CO2 equivalents per 1000 properties in 2017-2018 to 357 net tonnes in 2018-19.
The 119.5 per cent increase, which made Hunter Water the highest emitter of CO2 among Australia's major water utilities, was due to the fact that it was required to include wastewater treatment plant emissions in its reporting.
The corporation recorded a slight drop in emissions to 344 net tonnes in 2019-20.
A 2009 Institute for Sustainable Futures study into the potential greenhouse gas emissions from the proposed Tillegra dam, which was scrapped in 2011, found it would be a significant source of increased greenhouse gas emissions.
The report estimated emissions from the 450-megalitre dam would be the equivalent of adding 27,000 cars to Hunter roads.
Mr Rumble said there would be a similar increase in greenhouse gas emissions if either of the two dam sites currently under investigation at Limeburners Creek and Upper Chichester went ahead.
"As the Institute for Sustainable Futures has noted in their report in relation to Tillegra Dam, 'a sustainable water strategy for the Lower Hunter, based on improved water efficiency and water conservation measures, could reduce greenhouse gas emissions by an estimated 1.5 million tonnes of CO2-equivalent over a 20-year period.'," Mr Rumble said.
"Any new dam would have a similar problem. New supply options should be sustainable and in line with other innovative practices being implemented by other water utilities."
The Hunter Water spokesman said all supply and demand options remained on the table and no decisions had been made about which of the options would be included as part of the Lower Hunter Water Security Plan review.
The full National Performance Report for 2019-20 is scheduled to be released by the Commonwealth on 25 February 2021.