Long-term illegal storage of items in the Mulberry Grove Reserve car park is denying the public access to the site.
Aotea Great Barrier Local Board wants owners to remove their belongings.
"The car park is being treated as a long-term storage area, with people leaving boats and trailers on site, which is displacing day-users of the reserve," board chair Izzy Fordham says.
"Some of the stuff on the reserve has been there for years, and we need to clean it up because people are being put off from using the area. Sometimes there might well be the need to park on the road reserve but if the items go, there will be more room for cars and trailers."
During the school holidays, photos were taken that highlighted the items causing a lack of space in the car park, and how that results in 'creative' parking with cars on the road reserve, under trees and on either side of the barbecue and picnic table.
Owners of vessels or trailers stored long-term in the car park are urged to remove them.
Community Facilities will be serving notice with further action pending for those who do not comply.