An estimated 28 private properties, and several iconic beaches, are at imminent risk of being washed away in the next five years according to an alarming report into WA's coastal erosion, released on Monday.

Port Beach in North Fremantle and South Thomson Bay at Rottnest Island are among 55 locations identified in the state government's Coastal Erosion Hotspots report, expected to be "significantly impacted" by coastal erosion in the next 25 years.

Erosion at Seabird (left); a resident surveys the damage from above.

Premier Mark McGowan said it would cost around $110 million over the next five years to manage the locations, and called on the Federal government to help fix the issue.

"WA has more than 20,000 kilometres of coastline and the issue of coastal erosion is not going away," he said.