To the east of Bald Hill as far as Merriang Rd and south as far as Donnybrook Road is the nationally significant biosite Bald Hill.
The Bald Hill site has National significance for fauna on the basis of the presence of species such as the Grassland Earless Dragon seen by Beardsell in October 1988 along the Merri Creek escarpment. There has only been the one sighting due to difficulties in finding the species. The suitability of habitat along both sides of the creek for the Grassland Earless Dragon has been remarked upon in all reports.
The site’s rocky grassland appears to be prime habitat for the Striped Legless Lizard. However, the species has not been recorded in surveys of the site, although it has been recorded from the local area to the north and south of the Bald Hill site.
Amongst other significant fauna species, Plains-wanderer was sighted on rocky grassland in “Braelands” in the summer of 1983 and is likely to still persist.
Bald Hill has a number of other significant bird species due to the River Red Gum Plains woodland on the site. These include Tawny Frogmouth, White-winged Triller and Rufous Songlark. The Buff-banded Rail, Brown Quail and Latham’s Snipe were also observed in Poa grassland in freshwater meadows.
Schulz and Webster note that the present high faunal values of the Bald Hill site are due to its size and remoteness. Any future management of the site which saw it subdivided into urban or farmlet development would significantly reduce its faunal values.
A critical element of future management of the site will be preserving populations of the Grassland Earless Dragon. There is concern over whether it still survives in the locality as it was not recorded during pitfall trapping studies in 1995. Beardsell noted that in recent years the habitat of the Grassland Earless Dragon along Merri Creek within the Bald Hill site has been heavily grazed by sheep with a consequent reduction in grassland cover and that these conditions, together with an increase in fox numbers, are not conducive to the Grassland Earless Dragon’s survival.
Schulz and Webster’s report also makes the recommendation that weed invasion problems (especially Cape Broom and Serrated Tussock), associated with disturbance during installation of the gas pipeline, which crosses the creek adjacent to Bald Hill, be addressed.
Schulz and Webster describe the section of Merri Creek within the Bald Hill site as containing sections of rock riffles, tessellated basalt pavement, rock shelves forming small waterfalls and open water, pools and escarpments adjacent to Bald HillBeardsell records that one of only two known populations of Freshwater Blackfish in the Merri Creek occurs in the reedy pools upstream of the railway bridge. Although there is no operational discharge from the Sewage Treatment Plant at Wallan to Merri Creek, Beardsell has questioned its impacts on water quality as unlikely to be favourable to the Blackfish and observed that stream management to improve water quality and protect the Blackfish is required.
Beardsell believes that the Bald Hill site is a critical component in the linking of regional habitats, being between sites to the north, south (e.g. Craigieburn grasslands) and south-east (Darebin and Barbers Creek headwaters). He recommends that conservation management of the Bald Hill site is critical for the successful movement of fauna in the Merri Creek valley. “The long term viability of faunal populations at Craigieburn Grassland depend on protecting upstream native grassland habitat links.”.
Flora and fauna [T1]survey work was undertaken by Larwill et. al. in 1994 as part of the background work for the preparation of the Site Management Plan. They were unable to find Grassland Earless Dragon or Plains-wanderer.
The flora of the Bald Hill site is of at least State significance, due to the presence of Carex tasmanica and Psoralea tenax. Based upon the area examined by Frood, the site can be said to possess five vegetation communities ranging from Danthonia grassland to riparian scrub.
This site requires further floral assessment as Frood’s survey work only contained limited sampling (nine quadrats) and the extent of the better quality remnant vegetation was not fully determined, nor mapped.. The quadrats sampled by Frood were from along Merri Creek and land to its south, and along land to the east of a drainage line situated to the east of the railway line. It was the sample on the drainage line, which Frood described as a Grey Clay Drainage-Line Complex, which contains Carex tasmanica and was recommended by him for maintenance of its population as a priority
At Bald Hill, like many other areas in this vicinity, there is some stock access to the creek from insufficient fencing on both sides of the stream. The creek is fenced on one side alternately providing some protection of escarpment areas and the riparian zone. River Red Gums also appear to be dying from salinity related causes. There is also some evidence of bank slumping where stock have trampled vegetation.
Much of the significant grassland vegetation at Bald Hill is on or adjacent to land which Boral Resources has an interest in quarrying. Boral owns sites on both sides of Merri Creek and has a proposal for two quarries, one each side of the creek. A Donnybrook Quarry Site Management Plan was developed in 1997 but it was never finalised or implemented. Unfortunately, grasslands on the site have not been well managed. It is important that this site should be properly managed.
Larwill et. al. extended the number of flora species listed by Frood.
Bald Hill itself is recorded as a site of regional geological significance, although it is not included in the biosite.
 Biosite 3610 Biosites Maps and Reports – Port Phillip Region – 2005 CD.
 Beardsell, 1997, vol. 2, p. 35 Print Version of CD; also Schulz and Webster, 1991, p. 14; Larwill et. al., 1994, p. 44