But accommodation providers are confident loyal visitors will still choose to spend the summer at their sites.

Lake Eppalock Holiday Park owner and manager Peter Rose estimated he’d received 30 – 50 calls a day since Goulburn-Murray Water issued a warning about high levels of algae in the two bodies of water.

People were concerned about how it would affect their holiday plans.

“We’ve been getting quite a few cancellations,” Mr Rose said.

Up to 1200 people stay at the park between Boxing Day and Australia Day.

Mr Rose said the algae had affected 15 – 20 per cent of the park’s turnover. 

But it wasn’t all doom and gloom, with extra activities planned to keep people entertained.

“People that are long-time clients of the park, it doesn’t seem to worry them,” Mr Rose said.

He did not expect the algae to affect an annual fishing competition to be held at the park on December 30.

The event raises up to $4000 for the Mosquito Creek Fire Brigade each year.

Allison Allen, of the Lakeshore Caravan Park, said there had been no cancellations at the site thus far.

But she too had received “quite a lot” of calls from concerned clients.

Ms Allen expected people would still choose to holiday at Lake Eppalock, regardless of the algae.

“The majority of our park is annual site holders,” she said.

“A lot of people in the park know, if it’s there, what to do.”

She said others were waiting to see how severe the algae was before changing their plans.

While some people had been spooked, Welshman’s Reef Water Sports Club / Caravan Park caretaker Mark Shatwell said others had seized the opportunity to secure last-minute bookings.

He expected people would still give water sports a shot, as long as it was safe to do so.

“It’ll all be happening,” Mr Shatwell said.

GMW has advised people to avoid direct contact with the water at both locations and to seek an alternative water supply.

Blue-green algae contain toxins that can cause rashes, itchiness, asthma, numbness of lips and limbs, nausea, vomiting, diarrhoea, and sore eyes, ears and nose.

People should not eat any mussels, yabbies or crayfish from algae-affected areas.

Stock and pets should also be kept away from the water.

Goulburn-Murray Water says it is not known how long the blue-green algae will remain at high levels, but cool, cloudy and windy weather does help to reduce blue-green algae levels.