THE Airlie Beach lagoon will not be open for two of the region's biggest events with Whitsunday Regional Council announcing today repairs would not be complete until late August.

The Whitsunday Reef Festival, which uses the lagoon for its Recyclable Regatta, and Airlie Beach Race Week are two major events held in early August which reel in an abundance of tourists to the region.

The lagoon buildings and structure were significantly damaged when Cyclone Debbie crossed the region on March 28 and on the night of March 29 sewage from the Cannonvale pump station and nearby toilets overflowed into the pool.

After it was drained however, further issues such as concrete cancer were discovered.

Mayor Andrew Willcox said recent reports showed the structural integrity of the lagoon had been compromised and it was therefore unsafe to open to the public.

"The lagoon has copped a battering and required a detailed inspection by engineers to both assess damage and also report on normal deterioration and maintenance required," he said.

"The preliminary inspections have revealed structural damage, concrete cancer and drumminess of the pebblecrete, which requires the entire pebblecrete surface of the lagoon to be resurfaced."

Whitsunday Reef Festival chairwoman, Margie Murphy, said the lagoon had previously been a great asset to the festival as it helped to showcase the whole of Airlie Beach and its attributes.

"(But) we were under the assumption that the lagoon wasn't going to open in time so we requested to not run (the recyclable regatta this year)," she said.

Nonetheless Ms Murphy said even though festival organisers weren't planning on using the lagoon for a specific event anymore, "tourists do come here during festival time so it's a shame not to have it ready for then".

Despite finding the news "disappointing", Tourism Whitsundays chief executive Craig Turner said he understood if the council could open the lagoon sooner, they would.

"We understand (council) is doing everything they can and it's unfortunate but that's what has to happen," he said.

"(The lagoon) is critical to what we offer in Airlie because it's a great place for visitors and for locals to relax (however) the works required to be done are not ones of choice, but ones of need."

Cr Willcox said major works were being performed as quickly as possible so the lagoon could be opened to the community and visitors in August.

"Our focus has been on delivering the required outcome in the shortest timeframe from this forced short term pain, so that when the lagoon reopens it is a renewed, safe and functional attraction for our community and visitors to our region," he said.

The lagoon will be closed for a further 10-12 weeks and in the meantime, Cr Willcox said pumps were being replaced and repaired.