Residents of the Lower Hawkesbury are gearing up for a meeting with Central Coast Council Administrator, Rik Hart, on September 24 to discuss their concerns over a possible major spillage at Mangrove Creek Dam.
River Cares President, Robyn Downham, said residents are concerned at the possibility of water being released from Mangrove Creek Dam simultaneously with the Warragamba Dam during the next weather event, after a local holding tank overflowed during heavy storms earlier this year.
“We will be looking to discuss possible danger posed to the general public in the Upper and Lower Mangrove, Mangrove Creek and Greengrove areas,” Downham said.
“We would also like to review and discuss the current Emergency Dam Procedures and SES procedures on how residents will be notified of any danger if the telecommunications go down as they have previously.
“We would like to see a warning system established, such as a siren to warn people in the valley and surrounding areas.”
Downham said Member for Robertson, Gordon Reid, would also attend the meeting to discuss poor telecommunications in the Lower Hunter area, especially in Gunderman, Cohens Creek, Oyster Shel Road and Mangrove Creek Rd.
Hart said it was unlikely a spillage could result in flooding.
Downham said residents had received an alert on August 4 stating that the Mangrove Creek holding tank (at Pembertons Hill Rd) had burst and was losing water.
“This was alarming news to say the least,” she said.
She was advised by Council at the time that the incident was the result of an old pressure valve failing to open after 30 years of service.
The tank had not burst but had to be left running to ensure water supply to Somersby treatment plant and the community, she was told.
She was told a new valve had been installed and would be serviced every 12 months.
A Council spokesperson said the operations of Mangrove Creek Dam would be explained at the meeting and the Dam Emergency Plan would be introduced.
“The Emergency Plan provides guidance for the management of various emergencies including flooding,” the spokesperson said.
“The Plan outlines the water levels that trigger activation of the Plan and notification to other agencies, such as the NSW SES.
“Council staff at the meeting will explain the roles and responsibilities for agencies and Council, including who will communicate to the residents in the event of an emergency.”
The spokesperson said Mangrove Creek Dam is a storage dam not a flood mitigation dam.
“Storage dams catch the water from rainfall, as well as run off in the catchment,” the spokesperson said.
“Effectively, what rainfall falls into the dam through rain events also falls into the downstream creek and catchments.
“Communities located along the banks of Mangrove Creek and the Hawkesbury River, regardless of the existence of Mangrove Creek Dam, are vulnerable to flood risk from these large catchments.
“At the meeting on September 24, Council staff will also be able to talk through the functions of the dam in regards to the recent rain event.”
The meeting will be held at Spencer Community hall at 9.30am, with Kariong-Somersby Rotary Club to provide a sausage sizzle.
Terry Collins