The hot weather has led to the deaths of ‘large numbers’ of fish in East Northamptonshire.
Officers from the Environment Agency also say the recent high temperatures have caused an outbreak of blue-green algae at Thrapston Lake and are warning people not to enter the water.
Area duty manager Deborah Campbell said: “Our officers have been on site at Thrapston Lake this week following reports of large numbers of dead fish in the lake.
“We have determined that these fish deaths were caused by low oxygen levels in the water, which occur naturally in periods of hot summer weather.
“There has been no evidence to suggest that there’s been a pollution in the lake.
“While on site we took samples of the algae in the lake.
“Following testing, we have confirmed that there is blue-green algae present in Thrapston Lake.
“Warning signs have been put in place to inform the public and we are advising people to keep themselves and their pets away from the water in the lake as a precaution.
“We’re continuing to aerate the lake over the weekend to protect the fish stock that is still alive and we are planning to start removing dead fish at the beginning of next week.
“As the warm weather continues, we’d ask anyone who spots signs of fish in distress to please report it to our 24-hour incident hotline by calling 0800 80 70 60.”
Blue-green algae are capable of producing several different toxins.
People and pets may be exposed to these toxins through contact with the skin (such as when swimming), through inhalation or by swallowing contaminated water.
These toxins can cause skin rashes, nausea, vomiting, stomach pains, fever and headaches.
Occasionally they can cause more serious illness such as liver and brain damage.
Children are at greater risk than adults of developing problems because of their comparative lower body weight.