THESE are the pictures that have come back to haunt opponents to northern beaches sea defences.

Hundreds of protesters can be seen lining up in 2002 to prevent the building of a mooted sea wall in Collaroy.

The same stretch in fact, where $20m of property could be bulldozed.

Emergency crews and volunteers are hastily trying to protect waterfront homes from collapsing with rocks and sandbags.

Last night more than 500 people worked to keep the sea at bay after foundations were undermined by a wild weekend of storms.

media_camera The sea wall was never built after the protests.

media_camera The residents lined up as long as the proposed sea wall. Picture: Joe Murphy

Residents have been evacuated and homes taken off the real estate market but it could all have been avoided.

Now the council is having to dip into emergency funding to build a wall, and the homeowners will also be asked to fork out.

The Line in the Sand rally was organised by Surfrider Foundation Northern beaches boss Brendan Donohoe who stood in front of crowds of anti-development and surf-loving activists telling them sea walls would “actively destroy” the beaches instead of protecting them.

The protest was backed by the growing greens movement at the time and successfully pressured the then Warringah Council to knock back the protective walls.

“Sea walls do nothing to ensure the ongoing conservation of the beach in front of them,” Mr Donohoe told crowds.

media_camera Collaroy homes along Pittwater Rd have been cordoned off today. Picture: Toby Zerna

media_camera Homeowner Tony Gagorski' is allowed back into his home with an insurance assessor to check on the damage. Picture: Toby Zerna

media_camera Large boulders are dropped in place at the end of Ramsay St to help secure an apartment building under threat. Picture: Toby Zerna

“Worldwide experience shows us they actively destroy it.”

Surfers also complained the sea wall would ruin their perfect waves.

The newly amalgamated Northern Beaches Council today refused to admit they had made a mistake by laundering to a few heated protesters but confirmed a wall would be built at any cost.

Further up Collaroy Beach developer Phil Franks “went broke” fighting Warringah Council to keep a seawall outside his old home that he believes saved it this week.

He built it in 1997 following a storm but it was unapproved, so council sought a court order for its demolition. He fought and won, with the Land and Environment Court dismissing the council’s application to have it demolished.

A number of properties in the affected strip were set to be auctioned but have since been taken off the market.

media_camera This home was set to be auctioned next weekend but has since been taken off the market and its owners cannot yet return. Picture: Toby Zerna

media_camera Residents and emergency services sandbagging houses exposed to the king tide at Collaroy Beach last night. Picture: Dylan Robinson

media_camera The homes were smashed after the east coast low on the weekend. Picture: Braden Fastier

One of the homes, 1134 Pittwater Road, is believed to have lost part of its garden but otherwise remains intact.

It had an auction price guide of $3 million and was set to go under the hammer this weekend.

A home at 1112 Pittwater Road, which had a price guide of $3.6 million, was also taken off the market although it was not damaged by the storm.

Council has a history of buying property on the strip, including No. 1146 which was bought in 2005 for $2.97 million.

The council demolished the home that sat on the block and turned it into open space, devastating the previous owner.

“It has been my home for 20 years,’’ John Howell told the Manly Daily in 2005. “I’ve raised my children here and there are so many memories. I was numb at first and my children were devastated.”