Measures are being put in place to keep Dorney Lake free from toxic blue green algae (BGA).
BGA was identified at the lake, which is owned by Eton College, in mid-September and warning signs were put up for visitors.
The algae can release toxins that are harmful to humans and pets and Eton College sought advice from the Environment Agency and an aquatic plant specialist.
Recent wind and rain have helped clear up the algae and the college is putting in place additional measures to combat it in the future.
The water is safe for humans, but there may still be a risk to dogs.
Warning notices will stay in place until the veterinary authority gives the all clear.
A spokesman for the school said: “The measures taken were also informed by guidelines issued by the World Health Organisation and British Rowing.
“The College is purchasing ultra sound technology to control the formation of BGA. This should mean that the problem is less likely to occur.”
The college has not confirmed the cost or when the technology will be installed.
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