Dr Young has recently published her new book on the topic, the result of research and exploration of the swamps within the water catchment around the Sydney and Illawarra region as far back as 1978.

She said the swamps, which are classed as endangered ecological communities also act as “storehouses” for thousands of years of climate and fire records.

And they signal impacts from longwall mining underneath, which is increasingly frequent in the Illawarra’s catchment swamps.

“The upland swamps are the first warning we get about an impact on the water supply on the plateau surface … because they react immediately a longwall goes underneath them,” Dr Young said.

“And it’s actually very easy to measure the water table within them – you just have to put a small pipe in them and measure the water table. That drops from the surface down to the bedrock in days or a couple of weeks of the longwall going underneath.

“So they’re the flag that there’s an impact; the next thing is to work out how widespread the impact is across the catchment.”

“They store water as rain falls and runoff comes into them, and that water just seeps out during the dry period, supplying little headwater streams during dry weather. That’s important hydrological as well as ecologically. They drought-proof this end of the catchment. 

I think we’re seeing more widespread effects. The longwalls … are all cracking the surface, and draining the water, not just out of the swamps but also the streams. 

“The water drops below the base of the swamps and below the base of the creeks – and therefore it doesn’t end up in our water storages.

The more longwalls we have, the more widespread this impact is going to be. What we don’t know [yet] is exactly what proportion of that water is being lost.

Dr Young said her book was a tribute to the researchers and environmental advocates who had worked to understand and protect them.