Sydney's Northern Beaches face evacuation as a dam looks set to overflow

Manly Dam in happier times. Photo: Simon Thomsen

Residents around Manly Lagoon on Sydney’s northern beaches are being told they may have to evacuate as heavy rain forces authorities to open the floodgates at Manly Dam.

State Emergency service workers and police have been door-knocking residents along low-lying areas where a creek from the dam leads down to the lagoon and the beach at Queenscliff, where prime minister Tony Abbott serves as a lifesaver.

Residents have been told to they may need to evacuate their homes if the dam gates are opened to protect the wall from damage. The 1892 dam was used as a local water supply until 1933 and is now a recreation area and war memorial site.

Authorities say properties along Riverview Parade, Lakeside Crescent and Palm Avenue, parts of Pittwater Road in North Manly, Atiken Avenue in Queenscliff, Campbell Parade in Manly Vale, and Eurobin Avenue, Iluka Avenue, Bonner Avenue & Cameron Avenue, Golf Course Parade and parts of Pittwater Road in Manly are likely to be affected by potential flash flooding if the release occurs and evacuations in some areas near the Manly Lagoon have been made as a precaution.

Manly Dam to the coast. Source: Google Maps.

Flooding is likely because heavy seas pounding the coast are preventing the water from escaping the lagoon. Residents in the affected areas have been told to raise furniture and valuables to parts locations of their houses.

Northern Beaches commander, Detective Superintendent David Darcy said residents should remain calm.

“State Emergency Services, local council officers and Police have personally spoken to all residents that are likely to be evacuated in the event of an emergency,” he said.

The Harbord Diggers club is the evacuation centre.

The cyclonic east coast low lashing seaboard has caused havoc and widespread damage between Newcastle and Wollongong, with three people dead, and has been described as the worst in a decade.

It severe weather is expected to continue through Tuesday night, with the Central Coast and Newcastle expected to bear the brunt of the strong winds and heavy rains.

For help, call the SES on 132 500 or in emergencies, Triple Zero (000).

Police have also set up an 24-hour information line for anyone needing advice. Call 1800 227 228.

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