City compliance and environment manager Mark Gardiner said warmer weather, lack of rain and high nutrient levels were keeping blue-green algae readings high.

Council’s health warning to avoid contact with the lake remains in place, but Mick Henderson from the Wagga Boat Club said people were still using it.

“The number of users is down by 85 or 90 per cent,” Mr Henderson said. “People can still use the lake at their discretion, but it’s going to be a long winter for the club.”

While council was investigating ways to reduce the amount of algae, scientists continued to warn of the health risks of exposure to blue-green algae.

Professor Gilles Guillemin from the Motor Neurone Disease Research Centre had been conducting investigating the high rate of MND in the Riverina and said studies indicated people who spent significant time around blue-green algae were at an increased risk of contracting the debilitating disorder.

Dr Rachael Dunlop, an associate of Professor Guillemin, told Fairfax Media that research confirmed suspicions of a link between MND and the algae by replicating conditions first seen in Guam in the 1960s.

“The villagers had an MND-like illness,” Dr Dunlop said. “We replicated the illness using a toxin found in blue-green algae and found it caused ‘brain tangles’.”

Dr Dunlop said brain tangles were clumps of proteins most commonly seen in patients with MND, Parkinson’s and Alzheimer’s that caused brain cells to die. But she also cautioned people not to panic, saying if the toxin was the sole cause of MND there would be far higher numbers in affected areas.

“Blue-green algae doesn’t always produce the toxin,” Dr Dunlop said. “There may be other factors as well, like faulty genes or other trauma. People just need to be aware it is a risk factor and take precautions.”

The National Health and Medical Research Council (NHMRC) guidelines advise people and domestic animals should not come into contact with water containing blue-green algae.