Eprapah Creek and the Southern Thornlands Priority Development Area

Eprapah Creek is a story of survival. Despite what we have done to it over the last hundred years or so, it is still beautiful in parts, with natural vegetation and water tumbling over sandstone rocks that look as if they have been designed by a landscape artist.

The creek still maintains amazing plant diversity with beautiful examples of mature littoral rainforest trees, huge eucalypts and even an endangered plant, the critically endangered Native Guava¹ (Rhodomyrtus psidioides) which has been found along the creek. This is, unfortunately, in an area of future road reserve included in the Southern Thornlands Priority Development Area (PDA) recently proclaimed by the Queensland State Government.

Surveys of animals of the creek have shown similar diversity and value. The importance of the creek as koala habitat and for fauna connectivity are well recorded elsewhere. 297 species, including the vulnerable Illidges’s Ant Blue Butterfly², were recognised in the Eprapah Creek Waterway Management Plan of 2004 (Redland City Council). Another survey in 2010 showed the creek to be a hotspot of invertebrate diversity with the reason being: “the higher invertebrate diversity at the Eprapah Creek Corridor site was in all cases attributed to the presence of riparian rainforest.”³

The value of Eprapah Creek as a wildlife corridor of Regional Significance has been recognised by the State Government. The creek is indeed worthy of this designation as it connects the habitat areas of Point Halloran Conservation Reserve with conservation areas on Mt Cotton.

The map below (from Qld Globe) shows the main roads in orange and Eprapah Creek in purple from the estuary, then moving upstream, red, then brown and finally the tributaries in green. The approximate position of the PDA is shown in blue.

Note firstly, that the PDA covers virtually the whole north side of the middle catchment of Eprapah Creek (red and brown). Secondly, note the narrowness of the corridor in the lower catchment. Thirdly, the lack of vegetation in the middle catchment is largely because of agricultural enterprises (and no doubt land speculators hoping for better returns keeping their land free of regrowth). Even so there is still freedom of movement for fauna in this area which is arguably more advantageous for them than being forced into a narrow corridor as in the lower catchment.

Another point is that the PDA encompasses, not only the whole middle catchment of Eprapah Creek but also the sources of Hilliards Creek and Thornlands Creek. These sources should be protected and revegetated to safeguard the water quality of these creek systems which flow directly into Moreton Bay.

There have been many examples of fauna losses in the lower catchment of Eprapah Creek after urbanisation has occurred. Platypus were frequently to be seen in the lake formed by the old gravel quarry before the Victoria Point Lakeside Centre was built some twenty years ago.⁴ Koala numbers have declined markedly with the urbanisation in the lower catchment limiting their ability to move to other habitat areas. The decline of the koala population in the Koala Coast has been attributed to the loss of habitat and habitat connectivity through urbanisation. The vulnerable⁵ soft-spined rainbow fish has not been recorded in the lower catchment since 2004. It is notoriously sensitive to urbanisation, preferring unpolluted water.

The lack of a wider vegetated corridor in the middle catchment makes the remaining narrow strip of vegetation even more vulnerable to the effects of urban runoff. Examples of these effects on the creek itself where urbanisation has occurred in the lower catchment are illustrated below. The most insidious change in the lower catchment has been the increased runoff from urban development.

Runoff from the stormwater from residential developments in the lower part of the catchment has led to severe erosion. Channels as deep as 4 metres have been gouged out of the creek bank, even in the relatively open park residential developments.

As a result of this erosion the large trees are undermined, then fall into and across the creek. This is seen in many parts of the lower catchment where the fallen dead trees are numerous.

The reality is that it is impossible to build 8,000 houses with all the associated infrastructure of roads and other hard surfaces without increasing the stormwater runoff exponentially. The PDA report seems to place great faith in Water Sensitive Urban Design (WSUD) but its benefits are limited. Any engineer or hydrologist will tell you that nothing can stop runoff – it is simple physics. Rain falls and it has to go somewhere and is increased when there are hard surfaces. Measures such as retention and detention basins are only effective in small to medium rain events – once the basin is filled there is little benefit as the new runoff simply flows over the top as if the basin was not there.

Besides, such engineering measures are not without their costs to the environment. In the development of this retention basin in the lower catchment pictured below, bushland was lost and wallabies were killed – trapped behind the fence when the big machinery rolled in.

Eroded soil also washed into neighbouring properties as well as into the creek and eventually into the Marine National Park at the mouth of the creek. The problem of stormwater runoff is compounded by the steep slopes of the middle catchment which increase the velocity of the runoff, thereby washing away more soil. Only a very small portion of the PDA could be called flat land.

Most is quite steep as shown by the Redland City Council Planning Scheme overlay pictured below. The yellow colour indicates Landslide Hazard – the contours are also visible showing a height of 70 metres along Woodlands Drive down to 10 metres closer to the creek. The red line shows the approximate extent of the PDA. The blue/mauve depicts the flood prone area (pre-development). After development the flood prone area will widen markedly with all the extra runoff.

When the Matters of State and Local Environmental Significance and the Redland City Council Planning Scheme Overlays are added, it is obvious that there is not enough unconstrained land to accommodate the grandiose plans stated in the PDA Interim Land Use Plan (ILUP). The 8,000 houses plus a “thriving employment centre, commercial, mixed industry, schools and community facilities” are an impossible dream. The approximate position of the PDA is shown in black.

Just where are all these buildings going to be constructed? The only way that these unrealistic expectations may be achieved is by completely ignoring these overlays and having no regard for the future of the environment especially the endangered koala population and the integrity of Eprapah Creek. However, this is not what the PDA ILUP has promised. On page 14, it states that development will follow the “standards and guidance identified in the Redland City Plan 2018 Flood overlay code and Flood planning scheme policy”. The flaw in this course of action is that the flood levels will increase markedly after development.

The PDA ILUP also promises in the Environment section that:

#1. Development demonstrates location, design, construction and operation that avoids, or where this is not reasonably possible, minimises and mitigates adverse impacts on:

a. the environmental values of receiving waters
b. the habitat values of significant vegetation (including in waterways)
c. the ability for fauna to move along ecological corridors and across infrastructure
d. the ability for fish and other marine animals to move unimpeded along waterways,

And

# 4. Stormwater discharges:
…. will not adversely affect the hydrology of wetland and heathland ecosystems in a manner harmful to flora and fauna of those ecosystems.

This is plainly untrue. It is not possible to avoid these impacts as shown by the map above and the previous examples of what increased stormwater flow does to the creek. Obviously, the alternative is likely to be only minimisation and mitigation. Neither of these will save the creek from the massive increase in stormwater runoff as explained earlier. The integrity of the creek will be destroyed as the channel will widen with the loss of the thin strip of riparian vegetation and the biodiversity that goes with it will go, too. It will become a weed infested conduit for the stormwater that will come racing down the slopes. No amount of revegetation in the buffers will stop this process as it will not lessen the stormwater runoff from the hard surfaces.

Infrastructure (including roads, water and sewerage) is always more difficult and more expensive when it is obliged to accommodate to slopes such as these. The proposal to begin development with Precinct 1 will give a false impression of the difficulties to be encountered over the rest of the PDA as it is one of the few reasonably flat areas in the PDA. Hopefully, the overall increase in stormwater will be correctly calculated in the models before the development of Precinct 1. The southern part of this precinct is very close to the creek and is at the end point of the enormous increase in water flow from upstream after the development of the whole PDA. If the present flood levels are used to develop Precinct 1, there will be a massive problem in the future as these levels greatly underestimate the eventual flood levels from development in the rest of the PDA.

The PDA ILUP recognises that there is “limited capacity in the existing regional wastewater treatment and effluent management infrastructure to service development within the PDA” and that “development approved under the ILUP may require an interim wastewater solution that enables development to be approved prior to the completion of the DCOP” (development charges and offset plan). This means presumably, that sewage will be trucked away as has happened in other out-of-sequence developments in the Redlands. This has been occurring in southern Redland Bay for years. This is just not acceptable! Costings for the provision of sewerage and other necessary infrastructure may well prove to be prohibitive in this difficult site. It is still not clear who is going to pay for this expensive infrastructure.

In summary, the Southern Thornlands PDA is just not suitable for the dense development proposed. It is not possible to develop it without causing serious environmental harm to the catchments of the major creeks in the Redlands and to the endangered koala population.

The previous Redland City Council plan for the area was predicated on these factors with the lower impact development proposed far more suited to the area. It is hoped that Economic Development Queensland will realise this as further studies are done and return to the more realistic local plan.

Lynn Roberts BSc (AES)
President of Eprapah Creek Catchment Landcare Association (Inc) – ECCLA – since 2004

Eprapah Creek Catchment Landcare Association (Inc) (ECCLA)

ECCLA is an incorporated community group, formed in 1990, that achieves its aims through cooperation with stakeholders including landowners (especially the Scout Association), industry groups (poultry industry and shopping centre management), wildlife groups and local and state governments.

ECCLA’s goals are:

• to raise awareness of issues impacting on Eprapah Creek Catchment and other Redland Catchments and to make recommendations to address these issues
• to work towards sustainable land management through education
• to assist in the preservation of wildlife corridors
• to assess the health of the catchment and monitor changes over time

For over 15 years, we carried out water quality monitoring along Eprapah Creek and its tributaries. During this time, we became familiar with most of the creek and its special flora and fauna (including aquatic life). This role has now been largely taken over by council with their “Creek Crew” volunteers.

Previous Coastcare funding enabled me to carry out a flora and fauna inventory of the Eprapah Creek Estuary. I was among the first to notice and report on the finding of a mass kill of marine crabs. Our group worked in cooperation with the Environment Department to find the illegal dumping of marine waste (Tributyl Tin). Our president at the time, Dr Bernard Stone was an expert witness at the court case which led to the prosecution and jailing of the perpetrators.

ECCLA obtained Coastcare (Federal) funding for the construction of a fishing platform to help avoid erosion of the creek bank in the estuary. The State matched the funding and the Redland Shire Council contributed by designing and building the platform.

Other projects of note included a partnership with SEQ Catchments which led to funding for the project: “Working with Eprapah Creek Catchment Landcare Association to restore the Carbrook & Moreton Bay Ramsar listed wetlands”. This has contributed to revegetation projects (including restoration of foreshore on Coochiemudlo Island) and a substantial weed control project on Eprapah Road upstream from the Madeira vine infestation at Kingfisher Road. Recently, some leftover funding was given to a worthy project in the Eprapah Environmental Centre for control of the prickly climbing Asparagus africanus.

Another project funded by a “Caring for Country” grant was to perform weed control and revegetation at the Kingfisher Road bridge crossing. This was successfully carried out with the assistance and advice of Redland City Council and the help from students from the Conservation and Land Management TAFE – Alexandra Hills campus. At that time, I was teaching Conservation and Land Management at the TAFE. One of the species discovered at the site was the critically endangered Rhodomyrtus psidioides.

Footnotes

1. EPBC ACT Listing Status, Listed as Critically Endangered as Rhodomyrtus psidioides (Date effective 12 December 2020). ↩︎
2. Listed as Vulnerable (Nature Conservation (Animals) Regulation 2000 (Queensland): September 2024 list) ↩︎
3. 2010, Dr Chris Burwell, Dr Christine Lambkin, Dr Federica Turco, Dr Robert Raven, Dr Geoff Monteith, Dr Barabara Baehr, Dr Aki Nakamura, Susan Wright and Dr John Stanisic, “Redland City Invertebrate Study – Eprapah Creek” ↩︎
4. Long term volunteer caretaker at Eprapah Scout Environmental Centre, pers. comm. ↩︎
5. Listed as vulnerable by the ICUN (International Union for Conservation of Nature). ↩︎

Published by Redlands2030 – 25 April 2025