May 2015

Are bay sediments a window to a city’s soul?

28.05.2015 - Posted by Rob Catchlove
Tim Flannery’s article “Bay of Action” in The Monthly describes his experience growing up on the Port Phillip Bay and his disappointment on the current health of the bay. Sydney is described as a shining example of how a city has improved its management of coastal and harbour zones.

Sunny day on Sydney Harbour

Sydney Harbour - regularly flushed by the clean oceanic waters of the East Australian Current (image sourced from TrekEarth)

I would disagree that Sydney has improved due to the reasons stated. In the 1990s Sydney built offshore sewer outfalls and a massive amount of nutrients are now mixing with ocean currents. However, it’s not affecting the beaches. Sydney Harbour has a very different ‘flushing’ regime compared to Port Phillip Bay.

But I do wonder if Tim Flannery is on to something here. There is strong public support for healthy beaches in Sydney – evident by Sydney Water planning to use clean beaches as a key pillar for establishing a Water Sensitive Urban Design (WSUD) program across the catchment and embed it within the organisation. Effectively, there is already a social licence in Sydney to do works that link to cleaner beaches.

Are bay sediments a window to a city’s soul? Where will this journey to create a clean and healthy Port Phillip Bay go next and how long will it take us to get there?

Do offset markets for nature really work?

25.05.2015 - Posted by Kane Travis
Recently we had a lunchtime talk with Associate Professor Sarah Bekessy who has been teaching in environmental studies and sustainability at RMIT University since 2004. Sarah is interested in the intersection between science and policy in environmental management, and spoke to us about offsets and whether offset markets for nature can really work.

Murrumbidgee river near Gigerline Nature Reserve ACT

Murrumbidgee river near Gigerline Nature Reserve (ACT) - close to the ~110 ha M2G Offset Habitat conserved to compensate for vegetation and habitat losses resulting from the Enlarged Cotter Dam (ECD) and Murrumbidgee to Googong Water Transfer Project (M2G) [photo source: David Reid, Dave's ACT]

This discussion took me back to my involvement in offsets when it wasn’t quite so fashionable and lacked the sophistication of some of the programs today. At that time, I managed the environment program over the Shepparton Irrigation Region and part of that role was to negotiate vegetation removal as a referral agency to local government. There were no real offset rules then and it was guided by what felt to be reasonable. If a species was considered vulnerable in the Irrigation Region, such as White Cypress Pine, I used a 12:1 replacement ratio. For common species, it was about 6:1. I also made it a contractual condition to have 80% plant survival at 2 years. I found I was often stuck between the developer, Council and local environmental advocacy groups, but on the whole I am pretty convinced we achieved a genuine net gain for the environment at that time.

So how does that compare to the way offsets are managed and thought about now?

It appears to me that a lot of people have been doing a lot of thinking and a glance at the literature shows hundreds of research papers on the topic. There is also no doubt that the State and Federal Governments have taken to it with enthusiasm and there appears to be a steep incline in the uptake of offset schemes nationally. However, as discussed by Sarah, there are some untenable assumptions in existing schemes which are undermining their benefits.

In a project we just completed for the Victorian Water Industry, which developed a framework for Water Quality Offsets, we used a set of criteria that aimed to manage these risks. For example, the proponent would need to demonstrate that any offset proposed will indeed provide an environmental benefit (additional to any planned works), will be appropriate in terms of timing, will be measurable, and enforcable.

Policies that allow habitat destruction to be offset by the protection of existing habitat are pretty much guaranteed to result in further loss of biodiversity. Similarly, schemes that allow trading the immediate loss of existing habitat for restoration projects that promise future habitat will, at best, result in time lags in the availability of habitat. This lag increases extinction risk, or at worst, fails to ever achieve the intended offset at all. When we are talking multiple decades to transition to mature ecosystems, a lot can go wrong in that time.

Due to the uncertainties about the way in which restored vegetation matures, the current thinking strongly suggests that the biodiversity bank should be a savings bank. Accrued biodiversity values could then be demonstrated before they are used to offset biodiversity losses.

As described by Sarah in one of her papers*:

“…the only workable and equitable system is one in which assets are banked for the future and trading is only possible once it can be demonstrated that assets have matured (reached ecological equivalence with whatever losses they are being traded against). The value of biodiversity assets (savings) should be demonstrated before they can be used to offset loss of biodiversity elsewhere. New investments could be sold to a party interested in liquidating an equivalent amount and quality of vegetation.”

Our discussion also touched on the fact that some things simply should not be for sale. Some things, such as critical habitat for listed threatened species, should not be tradeable.

“Offsetting is not a panacea for unbridled development and must be firmly established as the last and most costly step of the “avoid, mitigate, and compensate” hierarchy…” *

This principle is enshrined in EPBC Act offsets policy (and various state guidelines) – maybe the questions about offsets should include an assessment of how capable the industry and bureaucracy are at sticking to the rules?

The current implementation of offset programs seems to have advanced substantially, but it still isn’t perfect in my opinion. I recently heard an extraordinary example of a Koala offset being provided for in-road roundabout. I wonder if teaching the Koala road sense was part of the offset deal.

If you feel like getting into some heavier reading then Sarah’s publications can be found at this Google Scholar site, but if you are after an example with a pretty unique twist on expressing a view on offsets try this link

* Bekessy SA, Wintle BA, Lindenmayer DB, McCarthy MA, Colyvan M (2010), The biodiversity bank cannot be a lending bank, Conservation Letters vol.3, issue 3, 11 March 2010

The 'Enhancing our Dandenong Creek' program and Dwarf galaxias

18.05.2015 - Posted by Amanda Shipp
There are very few urban natural resource management projects that show how an intervention can not only halt decline in ecological health, but actually improve it. The Enhancing our Dandenong Creek program is one such project, with major benefits for the native Dwarf galaxias.

A pair of Eastern dwarf galaxias (fish)

A pair of Eastern dwarf galaxias (source:
Fishes of Australia)

Melbourne Water is the responsible authority for 8400km of Melbourne’s waterways, including Dandenong Creek and Melbourne’s major sewerage pipe system. Melbourne Water and the Environment Protection Authority (EPA) are working in partnership to improve the health of Dandenong Creek through a five year program consisting of four different projects known as ‘Enhancing our Dandenong Creek’ (EODC). The EODC program includes a range of projects that look at protecting the creek from pollution, improving its natural amenity, creating new habitat for threatened native fish, and mitigating uncontrolled spills in the area.

Following an investigation in Dandenong Creek, it was found the Emergency Relief Structure (ERS) didn’t comply with EPA policy. An ERS is an outlet within the sewerage system that will overflow into the drainage system when the sewerage system is filled above capacity. This normally happens in a heavy rainfall event due to illegal stormwater connections and infiltration, which fill the sewerage system beyond capacity. By the time it overflows into the creek during high rainfall events, it is highly diluted and predominantly stormwater. The purpose of an ERS is to ensure that diluted sewage does not normally spill onto a person’s property (see Melbourne Water's Sewer Spills video on YouTube).

A traditional response to this would be to construct a duplicate sewage pipe. However, research along Dandenong Creek found that even though the ERS didn’t comply with the EPA policy, the wet weather sewage spills were not a significant cause of pollution in the waterway. Key pollutants identified were heavy metals and chemicals from the drainage system, which present significant stressors on the ecosystem. In light of this, the EPA have agreed to defer the construction of a new sewer and work in partnership with Melbourne Water to assess, develop and design a program to protect public health and reduce pollution while enhancing the surrounding natural amenity.

As part of this project, Rhys Coleman at Melbourne Water is developing a plan to support the Dwarf galaxias (Galaxiella pusilla), a nationally threatened native fish that was once common and widespread in the area. Rhys aims to improve habitats using his extensive knowledge of Dwarf galaxias requirements - based on his own research at the University of Melbourne, and supplemented by a team of consultants including Alluvium.

The Dwarf galaxias has a natural range across southeast Australia. They are small freshwater fish (usually less than 40 mm in length) that live in slow moving, shallow freshwater habitats, such as wetlands, billabongs and small streams that contain dense aquatic plants. With a mostly annual lifecycle, a critical ingredient for their success is an ability to move between multiple sites along a waterway corridor (primarily during floods) to help sustain population numbers across habitats with varying spawning success from one year to the next. An interesting adaptation of Dwarf galaxias to the variable Australian climate is an ability to cope with short periods of habitat drying. During these times, they are able to survive in moisture pockets such as underneath vegetation, leaf litter or in crayfish burrows.

A project site, wet in September 2014 
A project site, dry in February 2015

Habitat drying at one project site, in September 2014 (top) and February 2015 (bottom)

My main role in the project is to understand the hydrology and water balance at each site, and to identify minor changes to former floodplain habitats that can be made to ensure there are appropriate water conditions for Dwarf galaxias. Visiting the potential habitat sites and seeing the quality of aquatic vegetation, water conditions and even some Dwarf galaxias larvae at one site, reinforces the incredible potential of this project.

We look forward to seeing the project progress and the re-establishment of a healthy and sustainable native fish population within an urban environment.

Recent SEQ rainfall event

11.05.2015 - Posted by Misko Ivezich
On Friday the 1st of May, south east Queensland had a major rainfall event with 300+ mm occurring over a few hours in some catchments. Minor to major flood levels were hit in many of the systems.

Wivenhoe Dam spilling

Wivenhoe Dam spilling

On the following Saturday morning, I did an aerial assessment in a small plane with Seqwater to assess the damage of the event. The assessment included the Mary River, Stanley River, Upper Brisbane River, Mid Brisbane River, Lockyer Creek and North Pine River catchments. We've been working closely with Seqwater to implement restoration works in all of these catchments.

These catchments are crucial for SEQ water supply, however they have some pretty major erosion problems, which impact on water quality. It was amazing to see the sediment plumes entering all the major dams (Somerset, North Pine and Wivenhoe). The assessment highlighted the ongoing importance of improved catchment and river management to help protect our water supplies.

Here are some more photos of the floods, sediment plumes and dams spilling.

Image of stream bank erosion on the Mary River adjacent to the town of Kenilworth

Stream bank erosion on the Mary River adjacent to the town of Kenilworth

Recent meander cutoff in the North Pine River

Recent meander cutoff in the North Pine River

Flooding along the Stanley River

Flooding along the Stanley River

Sediment plume entering Wivenhoe Dam

Sediment plume entering Wivenhoe Dam

Sediment plume entering North Pine Dam

Sediment plume entering North Pine Dam

Floodplain inundation on the lower reaches of the Caboolture River

Floodplain inundation on the lower reaches of the Caboolture River

Townsville Office Manager

6.05.2015 - Posted by Matt Francey
We are seeking to appoint a Manager of our Townsville office.

We anticipate the successful candidate will:
  • Provide leadership and management oversight to a team of scientists and engineers in Townsville
  • Have extensive networks within the NRM industry in Queensland
  • Use industry knowledge and/or a background in strategic planning to contribute to the strategic direction of Alluvium.
For a copy of the position description, a confidential contact for further discussion and application details, please contact Megan Evans on

About Alluvium
Alluvium is a niche business, recognised as one of Australia's leading consultancies in the management of water resources, rivers and catchments. We have core skills in waterway management, including water sensitive urban design, integrated water cycle management, environmental water assessments, and waterway design and restoration. We work across a spectrum of projects from policy and planning, through design and implementation, to monitoring and evaluation. We provide consulting services across Australia and internationally through our offices in Canberra, Brisbane, Sydney, Melbourne and Townsville.

We believe that the application of creative thinking, a commitment to effective engagement, and the adoption of robust science and practical engineering can effectively address the complex and interrelated threats to the natural environment and communities.

Our business is deliberately focussed on attracting, training and retaining highly skilled staff with a passion to work with clients and stakeholders on complex river, catchment and water resource issues. This focus and commitment has resulted in Alluvium being selected in the BRW/BOSS 50 Great Places to Work awards in each of the four years up to 2014.

To learn more about us, visit our People and Identity pages at