On 8th March 1974 Interim Development Order No. 51 (IDO 51) was gazetted to control development in the catchment area of Narrabeen Lagoon to protect the lagoon, predominantly by restricting the range of land uses permissible and establishing a minimum area for subdivision of land of 20 ha (ie 200,000 m2), thereby limiting the intensity of land use. Even though the majority of Belrose North is not in the catchment area of Narabeen Lagoon, IDO 51 applied to this area anyway.
When this order was put in place residents were told that it was a temporary measure (hence the word "Interim"), and it's restrictions would be lifted in about 6 months (that was in 1974).
These provisions have been carried forward into successive planning instruments to date and remain current in Warringah Local Environmental Plan 2000 (WLEP 2000). Subsequent to the gazettal of IDO 51, the Oxford Falls Valley, or portions thereof, has been periodically subject to investigation for release for urban purposes. During the late 1980s and 1990s this resulted in the release of a number of areas for urban development being in the vicinity of Cromer Road and Maybrook Avenue at Cromer; Wearden Road at Frenchs Forest and Red Hill. It also resulted in Council’s undertaking a Non Urban Lands Study (NULS) to guide existing and future uses in Warringah’s non urban lands. The study area broadly included land within the suburbs of Terrey Hills, Duffys Forest, Belrose, Oxford Falls and Cromer. Stage 1 identified areas of land that may be capable of increased development intensity and based these findings about land capability largely on slope and terrain, soils and erosion hazard.
This was done in 1998 by the Consulting company called PPK (now called Parsons Brinckerhoff). I have a scanned copy of this report, but it is 152MB (which is huge). Anyone wanting a copy of this report can send me a USB stick and I will copy it for them.
This was done by the Planning Assessment Commission in 2009. It looked into 4 sites for possible release as urban areas.