Do large desalination plants destroy marine habitats?

[Diver Sue]

In November, a large desalination plant producing 125 megalitres of purified water a day will get the go-ahead from the government.

As the brine outlet pipe will only be 1.8 km offshore and will deliver twice the salt content of seawater, I am very concerned there will be a lot of damage occuring to marine life.

Does anyone have any personal experience from before and after dives or are you able to direct me to relevant experts who can tell me if the various desalination plants around the globe - especially the larger ones - have made a big environmental impact on the marine life?

This plant is being built at the Gold Coast in Queensland, Australia. It will be in the majestic sweeping bay that is the Gold Coast. It is a natural nursery for a wide variety of fish and is currently pristine - great visibility, beautiful natural reefs not far offshore and whales come in very close to shore from July to November.

Before the final contract is signed, it would be great to have feedback from other parts of the world with a desal plant. Hopefully they are operating well, but if not,some real evidence of environmental damage would be greatly appreciated!

It's pretty urgent - your help would be greatly appreciated!

Diver Sue

 

[Nautical Dreamer]

Was an Environmental Impact Assessment ever conducted. If so I would imagine that salinity concentration plume would have been modeled and analyized. The analysis should have included an inventory of the marine organisms and their tolerances to differnet concentrations of salinity.

Here in the States there is usellay a public commenting period where this information is made availible before the constuction permits are granted.

 

[FredT]

Normal salinity concentrations are 35 ppt. Double that gives ~70 ppt. If there is ANY flushing current in the area and any kind of diffuser nozzle on the outflow pipe you'd be hard put to find concentrations above 40 ppt a half a click from the outflow point. Small salinity differences diffuses pretty fast in the open ocean unless there is a significant temperature difference too to drive stratification

 

[archman]

Historically, the major gripe with commercial-grade desal plants is that the effluent pipes were too close inshore. That, and the brine didn't disperse readily.

Sticking the pipe over a mile offshore seems prudent. If your water deepens out close to shore, even better.

After all "The Solution to Pollution is Dilution."

Desal plants are going to be popping up more and more in the near future. Freshwater is becoming a hotter commodity.

On the plus side, virtually all of the freshwater extracted from the ocean has to go back at some point. We just add a fun cocktail of chemicals and nutrients and call it "wastewater".

 

[Diver Sue]

The worry with this particular desal proposal, is that the State Govt has declared the need for clean drinking water to be an "emergency" and has thrown away any formal Environmental Impact Statement allowing for full community input including the ability of other scientists to applaud or question the findings of the company's own scientists.

It's frustrating that the scientists conducting this research are also paid by the company building the desal plant in the first place, and they are under no obligation to release any of their research of other plants, any scientific studies etc for public scrutiny and comment!

 

[archman]

I'm presuming that if the water is going into the municipal water supply, then the public has a right to access the EIS.

Contact your local legislator and request a copy of the report. Phrase your writing to be as polite as possible... but be sure to add the caveat that if the report cannot be forwarded, an explanation is put forward... and how to make viewing the report actually happen.

... if it isn't possible to view the report at present, would you please let me know who to contact to inquire further?

This way, if you get the runaround, you have a discrete person/office to pester with phone calls, petitions, and emails.