Category: News

Now, with desalination plants proposed at both ends of the scale — from a small unit at Port Hughes to the massive BHP proposal — questions are again being raised, this time, by Port Hughes and Moonta residents.

Revisiting the issue this week, YPCT found not much has changed — that scientists and desalination proponents are gulfs apart in their opinions on the safety of desalination in the waters surrounding Yorke Peninsula.

Precedent-setting

While the catalyst for action from marine scientists and conservationists was BHP’s plans for Point Lowly, locally, The Dunes’ plan for desalination at Port Hughes to water the Greg Norman golf course that the development hinges on adds another dimension with its precedent-setting potential for towns on either side of the gulf.

Port Hughes resident, Ron Sherriff, who has sat on a consultative committee looking at Marine Planning for Spencer Gulf and, until recently, ran a fishing charter business, says the uniqueness of gulf waters will play a major role.

“When I sat on that committee it was explained to us at the time that there were three different currents in the gulf running in pretty much circular movements because of the foot at the bottom of Yorke Peninsula. One current runs between Whyalla and Pirie in the top of the gulf, one runs between Wallaroo and Cowell and the bottom one runs between Tumby and Hardwicke Bays.

“I know there is a lot of tidal flow at Pt Lowly where the BHP desalination plant is proposed but the question has to be asked: does it leave the gulf or come back?”

Mr Sherriff says local councils do not have the expertise to make decisions on gulf waters.

“I don’t think they should be able to say yeah or nay to desalination plants in either gulf — gulfs are different to open water. Marion Bay is different because it is not within the gulf and there is a lot of movement in that area.

“If the Copper Coast council say yes to a desal plant at Port Hughes it sets a precedent for other towns and councils along the gulf’s coast and could affect the entire gulf waters.”

He says a combination of single-tide days and dodge tides during summe, means there can be very little movement of water.

“Certainly there is more movement and deeper water out past Cape Elizabeth and around Tipara Reef, but even then, there is little movement during the summer months.

“There needs to be a whole lot more independent research before desalination is approved.”

Scientific study

A lack of water exchange in the gulf and the potential for salinity problems has been a concern of local fishers — June Gill from Gill Fisheries flagged the problem in November 2006 — and recent research appears to support that.

Dr Jochen Kaempf from Flinders university’s school of chemistry, physics and earth sciences has been looking at the oceanography of both Spencer and Gulf Saint Vincent. He says desalination in both gulfs is “risky” and that further studies must be carried out.

In recently presented findings to the Onkaparinga Council (in relation to the Port Stanvac desalination plan), Dr Kaempf found that there is a risk of brine (high-saline water) becoming trapped in the near-shore zones, that there is risk of brine accumulating during dodge tides and a risk of brine being trapped on a gulf-wide scale in summer and that “a detailed and independent environmental assessment study needs to be carried out to address these risks including near-field and far-field impacts as well as short-term and long-term impacts”.

“On the basis of my expert knowledge (as a physical coastal oceanographer) I consider the release of low-oxygen brine into the gulfs as risky and potentially detrimental to marine life. Apart from the dodge tide problem, which could lead to local trapping of the brine, there is only little exchange of both gulfs with the ambient ocean during the summer months, and both gulfs are more like large isolated inland lakes during this time. Hence, there is only little overall flushing of the gulfs in summer and the brine can become concentrated.

“Owing to its shallowness and distance from the ocean, upper Spencer Gulf experiences little flushing throughout the year and there is a great risk of brine accumulation in this region”, Dr Kaempf said.

“Adelaide coastal waters, on the other hand, already show a relatively poor water quality (see Final Report of Adelaide Coastal Waters Study), and addition of low-oxygen brine would add another risk factor.

“Despite the current water crisis in South Australia, which cries for a solution, the construction of desal plants along SA gulfs (with release of brine back into the sea) may not be the most environmentally friendly solution to this problem.”

Local expert

Desalination at Marion Bay has been a resounding success for the District Council of Yorke Peninsula, says Yorke Regional Development Board (YRDB) Economic Development Officer, and local water expert, Peter Stockings.

Mr Stockings says he believes desalination can be done safely in the gulf but concedes there needs to be more research.

“I think desalination could be safe in the gulf with the right tidal movements and water depth.

“Not knowing Moonta Bay myself, I would still say that it would make sense to put the dispersional pipe into 20 metres of water, and if it’s far enough out, it should be okay.

“You do need to make sure that the brine is dispersed. I’m all for development, but it has to be sustainable. I think there does need to be extensive work on tidal movement in the gulf,” he says.

Mr Stockings is surprised that no-one from The Dunes development or the District Council of Copper Coast has spoken to the YRDB about desalination given the research put into the Marion Bay plant.

“No-one has spoken to us, but we would only hope that the Council would talk to us at the Board about any desalination plan.

“We went to people that are making desalination plants all over the world and got the information we needed — there is oodles of information out there on desalination.

“Certainly the plant at Port Hughes does not have to be sited by the boat ramp. Ours (Marion Bay) is tucked away in the bush — you just put a pipe in and pump the water up to it.

“As for concern about fish biomass — ours is not problem at all at Marion Bay, because we use a beach well and pull the water through that — the sand acts as a natural filter so you lose no biomass.”

BHP research

Mr Stockings is a representative on the Murray Darling Association (Region 8) and as such has access to information about the Olympic Dam expansion.

He says a recent presentation to the group indicated that discharge from BHP’s desalination plant would be one to one and a half kilometres out into Spencer Gulf into a depth of 20 plus metres and with high tidal flows.

“They plan to have a two metre diameter intake pipe which will allow for slow intake and minimise any effect on fish biomass,” he said.

“They showed that evaporation is taking more water out of the gulf than the desalination plant will and that local fish and cuttlefish can withstand higher levels of salt.”

In its public update advertising of October, 2007, BHP said its studies had looked at impacts across the whole of the Spencer Gulf, “not just on a daily basis but on what could happen over the next 50 years” finding that “results of the various analyses have demonstrated that the proposed desalination plant can be operated at Point Lowly without adverse impacts”.

An Environmental Impact Statement, expected by the State Government around August 2007 (YPCT May 1, 2007) “may be released later this year” according to a BHP spokesperson.�

Key points

* Local fishers say fish biomass would become part of the “intake” for desalination plants, and that gulf waters become trapped
* Oceanographers also say the gulfs have little water exchange with the ocean during the summer months and “both gulfs are more like large islolated inland lakes during this time”
* A “yes” to desalination at Port Hughes could set a precedent for other councils
* Marion Bay’s desalination plant is located at the foot of the gulf with good water movement
* Marion Bay uses sand as a natural filter to protect fish biomass from intake
* BHP says deep water and strong tidal movement makes its desalination plant safe
* BHP’s Environmental Impact Statement is still outstanding (was expected around August 2007)
8 Experts agree more research is neededæ´€

The long-term average for the three months of autumn since records began in 1862 is 132.3mm CSIRO report author Dr Wenju Cai said the climate study of the past 58 years showed two significant features.

The number of rain-inducing La Nina events were being increasingly outnumbered by dry El Nino events.

And subtropical Indian Ocean patterns influenced by global warming were diminishing autumn rainfall, particularly in May across northern Victoria.

“When you take these two components together it has a huge impact in the reduction of rainfall and inflows,” Dr Cai said.

“This is not only very important for agricultural but also in wetting the soils and ensuring there are good inflows in the usually wet months of winter and spring to follow.”

The report found that spatially alternating high and low pressure systems, known as pressure wave-trains, are crucial influences for rainfall over Victoria in May.

Such systems have been weakening since 1950.

La Nina transitional periods usually produce wet autumns in northern Victoria and southern NSW are become shorter.

Long-term climate is dominated by more extensive dry El Nino events, another strong indicator of climate change.

Dr Cai said the outlook was serious, and the consensus among scientists was that continuing climate change would reduce inflows by about 15per cent for every degree of warming.

Under the median estimate of a two-degree rise in temperature – which is conservative – there was likely to be a 30 per cent reduction in inflows for the Murray Darling Basin.

The sobering figures are vindication for Coliban Water’s conservative approach to its five-year water plan.

The plan is based on an expected reduction in inflows to the Campaspe system from the long-term average of 38 gigalitres to 15 gigalitres – or more than 60 per cent.

Department of Sustainability and Environment estimates show that surplus water under a ‘medium’ climate change scenario would be about 23 gigalitres by 2030.

The figure would drop to only 8 gigalitres by 2055.

A repetition or continuation of inflows of the past eight years would constitute a more extreme climate change scenario.

Goulburn-Murray Water strategy manager Garry Smith said the data highlighted the importance of the State Government’s Northern Region Sustainable Water Strategy, a draft version of which would be released in coming months.