Artefacts discovered at Warragamba and Cataract as water levels drop

In the lower Blue Mountains catchment area of Warragamba Dam, remnants of the region's past have emerged from their watery graves.

Locals have spotted a WWII tank and the shell of what used to be the Wollondilly Bridge.

A Water NSW spokesman said residents had "nothing to be concerned about" despite the reappearance of these items.

"The ongoing drought has resulted in the re-emergence of a wide range of heritage items around the lake foreshores and bottom of the lakes," he said.

"The items include wells, building footings from old farms, fence posts, old roads and bridges, railway lines, construction platforms and general dam construction remains.

"Old farm wells were recently highlighted at Lake Keepit."

Water NSW confirmed that the tank appeared to be a Medium tank M3 Grant - one of just 6258 made.

It wasn't uncommon for farmers to purchase used tanks following the end of WWII, to be used on their properties for things like land clearing.

The Wollondilly Bridge from the Warragamba catchment has made appearances in past droughts as well as the ongoing one.

Some of the most unusual items that have reemerged are the torpedo net poles up against the dam wall at Cataract Dam.

These poles held up nets that were placed to "catch" potential bombs before they exploded and protect the dam during WWII.

"These artefacts have no affect on water quality," the Water NSW spokesman said.

"It is best to leave these heritage items where they are found, especially if the dam is State Heritage listed.

"Letting the heritage items 'age in place' is appropriate and meaningful.

"The items do not need to be rescued, restored and/or placed in a museum."

These relics tell more of a story about early settlement, farming patterns and dam construction in the region.

While the items may be physically deteriorating during each drought, and one day may even disappear, Water NSW believes their reappearance gives a measure of how bad the drought is and a reminder of the history of the site.

The formerly inhabited Burragorang Valley was deliberately flooded 60 years ago in conjunction with Warragamba Dam's construction, after the government acquired all the homes and farms.

Last year the state government announced its plans to raise the dam wall to mitigate flooding in the Hawkesbury region.

Wollondilly Council and Blue Mountains Council have joined forces with community members to rally against the plan to raise the dam wall as it would allow development on a flood plain and flood sacred Indigenous sites and world heritage listed national park land.

Water NSW also confirmed that recent rains had a "negligible increase" on the Sydney water catchment.

Oakdale and Nepean Dam recorded 28 and 30 millimetres of rain respectively in approximately two hours due to storms last Sunday.

Preliminary observed data has average catchment rainfall across the Warragamba catchment area of approximately 11mm.

However Water NSW confirmed only very minor increases to inflows at the dams have been recorded .

"Negligible increase in total system storage is likely due to the dry condition of the catchments," the spokesman said.