The upgrade is one of seven State Water is managing throughout regional NSW to enable the storage to safely pass an extreme flood and ensure it is in line with NSW Dams Safety Committee standards.

State Water site co-ordinator Duncan Wilson said works to construct the four new fuse-plug spillway bays was almost complete.

"Construction remains ahead of schedule and on budget, with the fuse plug spillway bays still to be finished, as well as fencing, revegetation and removal of the temporary cofferdam," Mr Wilson said.

"The dam safety upgrades are in response to improved knowledge of extreme weather and rainfall since the dams were built and involve modifications to the dams, enabling them to withstand the biggest floods now considered statistically possible for the region. The fuse-plug spillway would only be triggered in the unlikely event of an extreme flood, and would work by safely overtopping and washing away in sections, to reduce the water level of the dam and protect the main dam wall."

The permanent road has been reinstated, following the completion of excavation during which a temporary road was in place.

"Repairs to Copeton Dam Rd are under way, after State Water and Inverell Shire Council reached agreement to address areas that may have been aggravated by the heavy construction machinery and increased traffic from the upgrade," he said.

The new Copeton Waters State Park facilities continue to be popular, with additional picnic tables installed to meet the high demand.

Copeton Dam's water level is at 91 per cent of capacity.