Cr Sabine Winton successfully moved an amendment to add lines about writing to developers with landholdings north of Two Rocks Marina, and to outline to the State Government its financial responsibility for erosion management.
A report by MP Rogers and Associates said construction of the marina in 1973 interrupted drift in the area, causing erosion to the north and sand build-up to the south.
It outlined two possible ways to manage erosion, one a managed retreat and the other to build two groynes.
The council authorised a presentation of the report and recommendation at a public meeting in Two Rocks, but has not specified a date.
During public question time, Quinns Rocks resident Natalie Sangalli asked if the council would voice opinions on future marinas, flagged in Eglinton and possibly Alkimos, given erosion north of the existing marina.
Wanneroo chief executive Daniel Simms said Ms Sangalli could write to the State Government.