The approval comes with restrictions which relate to mass participation events.

The restrictions include less available hours of road closures and restricted gatherings of spectators.

In a statement on the Triathlon NSW website, chief executive Adam Wicks said "this is the news we have all been waiting for" but some difficult decisions needed to be made in order for the championships to go ahead.

The junior club championships, including the TRYkids and the junior super sprint, and half club distance (500m swim, 15km bike, four km run) were cancelled.

"The decision to cancel the junior event was based on the fact that athletes under 16 always need to have an adult accompany them to the event site, raising issues with adhering to the NSW Health Order," Mr Wicks said.

"The half club distance is a significantly smaller event and to have additional road closures (during very busy times in the township of Forster) is not viable for both (race partner) Elite Energy and disruption to the movement of visitors wanting to use Main Beach, One Mile Beach, Forster Bridge and many cafes and heavily visited areas. These disappointing decisions were required for the event to occur, at all."

This week, competitors were briefed on the changes. They will adhere to an 'arrive, race and leave' plan.

The restrictions will also impact on volunteers. Organisers will determine the minimum number of volunteers required to run the event before opening up the positions.

Triathlon NSW reiterated the importance of barring spectators in the event site.

"Spectators are counted in the NSW Public Health Order, and as such, we ask that you don't bring any spectators to the event," Mr Wicks said.

"COVID marshals will be on site to enforce social distancing and minimise crowding and discourage spectators.

"If a COVID marshal asks your spectators to please move on, please deal with this situation with understanding and support. They are volunteers trying to help the event remain safe."

Mr Wicks said it's vital competitors work with police and the Great Lakes community to minimise the risk of spreading COVID-19.

"It's vital if the triathlon community wish return to the region for future events," Mr Wicks said.

He said the decision is a sign the sport is moving in the right direction.

"The onus is now on us, the athletes and custodians of the sport, to ensure we allow races to operate, by abiding by the rules," Mr Wicks said.

The event was originally slated for May before it was pushed back to September and finally November. This will be the first time Forster has hosted the championships since 2016.