As at 19 February 2001, The southern portion of Prospect Hill, located within the Boral Brickworks site has been extensively quarried; however the CSIRO site has largely retained its original surface form. Archaeological potential high within the CSIRO site. Long-term pastoral use on much of Prospect Hill has ensured the site retains its historical links and archaeological potential. However, Prospect Hill is under immediate threat from development, which has the potential to impact upon the significance of the site. This includes the rezoning of the site as part of SEPP 59 and development for residential/employment purposes, the continual quarrying of the southern portion of the hill; and new development proposals including a proposed flagpole to be erected on Prospect Hill commemorating Federation. Various modifications, extensions and refurbishment of buildings within CSIRO research complex over time. In 2002 Delfin Lend Lease entered a joint venture with Boral to develop the residential lands. This part of the estate is now known as Nelson's Ridge (after Nelson Lawson who owned the Greystanes Estate and commissioned Greystanes House in 1837). Nelson's Ridge is being developed by Lend Lease in two stages with the first comprising the northern employment and northern residential lands and the second comprising the southern equivalents.