Visitors to a popular reservoir have been told not to enter the water after dangerous blue green algae was found.

East Anglian Daily Times: The aqua park at Alton Water is going to be 'zapped' with ultrasonic equipment to kill the potentially toxic blue-green algae infestation Picture: AQUA PARKS GROUPThe aqua park at Alton Water is going to be 'zapped' with ultrasonic equipment to kill the potentially toxic blue-green algae infestation Picture: AQUA PARKS GROUP (Image: Archant)

The discovery of the toxins - which if swallowed can cause illnesses including skin rashes, eye irritation, vomiting, diarrhoea, fever and muscle and joint pain - at Alton Water means watersports and other activities will be cancelled.

The news has sparked dismay among many excited to visit the splash park after the 8,000 square metre site was revealed in May.

After the discovery on Friday, July 20, Anglian Water - which manages Alton Water - said it had “taken the decision to temporarily close the water sports facilities and the Aqua Park with immediate effect as a precaution”.

• Alton Water latest in string of blue-green algae victims as blooms thrive in heat

A statement on its website published shortly after 11pm added: “While we know this will be disappointing for people booked into the Aqua Park or expecting to use the water sports facilities, the safety of the visitors is our top priority.

“We will be testing the water twice daily and will reopen the facilities once algal levels return to normal.”

The statement said Aqua Park will be contacting people to reschedule bookings as soon as the algal levels are back to normal - but said it was likely to mean cancellations over the coming days.

It also said Water Sports Centre customers’ sessions would be cancelled and while that Alton Water’s campsite is still open to visitors, access to the water will not be allowed.

With blue green algae known to be fatal to pets, the statement added: “Please note dogs should be kept on a lead at all times and should not be allowed to enter the water at any point.

“We are sorry for the disappointment caused to visitors who will no doubt have been looking forward to their day out. We know the Aqua Park is hugely popular, as are the other water sports facilities, but algal blooms are a natural occurrence and therefore difficult to predict or prevent.”