LETTER TO THE EDITOR / Claims that a Daintree bridge is less damaging than a ferry


15 October 2020

Dear Editor

Members of Douglas Shire Sustainability Group (DSSG) have participated in the Douglas Shire Council’s process which is aimed at determining the appetite of residents and others for a bridge over a two ferry system, as a means of crossing the Daintree River.

As the arguments in favour of a bridge have been eroded, we have noted that proponents are sticking with two arguments to support their claim that a bridge is less environmentally damaging than a ferry.

Firstly, it is argued that dredging the Daintree River creates ongoing significant environmental damage (and a bridge does not).

There is no doubt that dredging is an environmentally sensitive activity, and it is heavily regulated in the Great Barrier Reef Coast Marine Park, by both the Queensland and Australian Governments.

In addition to the annual EPA Permit issued by the Queensland Government, Douglas Shire Council has a 10 year Marine Park Permit for dredging the river.  The application process for that permit must be accompanied by an Environmental Management Plan and an Operational (Site) Management Plan. These plans are used to identify and mitigate environment damage to both the dredging and receiving zones.

Douglas Shire Council will not release these plans, claiming they are prohibited from doing so by a clause contained therein: “This document is and shall remain the property of GHD Pty Ltd. The document may only be used for the purposes for which it was commissioned and in accordance with the Terms of Engagement for the commission. Unauthorised use of this document in any form whatsoever is prohibited”

We are very perplexed by this claim, especially when Council has commissioned the reports, paid for them and lodged them in support of their permit application. We are further perplexed when we see a number of reports published and promoted by Council on its website, containing this clause.

For example https://douglas.qld.gov.au/download/daintree_ferry/Daintree-River-Ferry-Traffic-Assessment-Traffic-Modelling-Report.pdf

We are pursuing release of the plans, so we can understand the full impact of the dredging, and how it has been successfully mitigated.

We have researched the impact of river dredging by reference to Reef 2050 Plan and the Reef Water Quality Improvement Plan (Great Barrier Reef Marine Park Authority), and established the sediment fraction that impacts the reef is the “fines” i.e. the small particles that remain suspended when river flumes go out to sea. The coarse components of the sediment are left in the rivers or on the beaches in the form of sand.

There is obviously a turbidity impact while the dredging occurs but it is short lived, localised and intermittent. 

The Reef 2-2- Water Quality Improvement Plan has found that “monitoring and scientific modelling have shown the main source of sediments from the Great Barrier Reef catchments is from agricultural land use, with grazing including gully and hillslope erosion accounting for nearly half of the fine sediment generated by human activity. The second biggest contributor is streambank erosion. Sugarcane cropping, non-irrigated dryland cropping and other land uses, such as urban, mining and industrial, also contribute but to a smaller degree”.

The second area used to support a claim that a bridge is less environmentally damaging than a ferry is the use of diesel to fuel the existing ferry.

The proposed new electrically driven ferry is to be partly solar powered, and recharged from mains power overnight. It will use no diesel and will have a fraction of the greenhouse gas emissions of the current diesel engine. 

Of course, a bridge is not fossil fuel free either. Every vehicle still needs to cross the river on a bridge, and collectively it amounts to more fuel burnt than what the ferry service uses. Depending on which bridge option is selected, travel times could be increased by as much as 25 minutes each way. That constitutes a massive increase in fuel use as compared to the ferry service.

Whilst we acknowledge the need to reduce fossil fuels, we can find no evidence that diesel fumes directly damage forest. If it did damage the forest, the evidence would be on the roadside where there is the greatest concentration of diesel exhaust fumes. We also note trees grow happily in inner city areas where exhaust fume concentrations are huge. There is also evidence that increased CO2 concentrations speed up plant growth – not surprising as that is what plants live off and is the reason trees are planted to pull CO2 out of the atmosphere.

And finally, the greenhouse gas footprint in a concrete bridge is huge.

According to the think tank Chatham House “…..Cement is the source of about 8% of the world’s carbon dioxide (CO2) emissions……If the cement industry were a country, it would be the third largest emitter in the world – behind China and the US. It contributes more CO2 than aviation fuel (2.5%) and is not far behind the global agriculture business (12%)” 

DSSG does not know how much concrete would be used for the proposed bridge and suggests Council should calculate the amount for the purposes of better understanding the climate footprint of the bridge, in comparison to a ferry that is partly solar powered.

Yours sincerely

Didge McDonald

President DSSG

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