The archery club bore site can only contribute three litres of water per second to council's goal of an absolute minimum overall volume of 9-10 litres per second. Drilling at the other four sites, including near Tenterfield Station, all came up empty.

Drilling on the current test bores will reach down to depth of around 136 metres. Council's chief executive Terry Dodds said this creates some technical challenges that keep the drill operators focused.

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"Compressed air is used to blow out the crushed rock. At 136 metres if any larger sized stones become prevalent, there is a chance that the compressed air isn't strong enough to blow the larger stones out of the drill hole.

"If these larger stones then end up between the drill bit and the bored hole, the rock pieces may cause the drill bit to become stuck."

Mr Dodds said after these test bores are finished the rig will move to the unformed section of East Street and The Common off Steinbrook Road. There are still other sites to the north of town but as the sites become more remote from Tenterfield Dam they become more expensive to pipe, and the piping will take longer to install as well.

As the days heat up the sense of urgency increases, with evaporation rates at the dam set to rise. Mr Dodds said that currently the dam is expected to drop 8.6mm a day during summer due to evaporation alone, more than twice the winter evaporation rate.

The cost for the test bores is now around $500,000. The emergency water project was first projected at $3.2 million, but Mr Dodds said this was an open-ended estimate as no-one knows what the final outcome will be with everything depending on where the water is found and how many sites are required.

The bill is being shared 75/25 per cent by the NSW Department of Industry and Water and Tenterfield Shire Council.