Warning over toxic blue-green algae hazard
The Environment Agency (EA) is asking people in Lincolnshire, Northamptonshire and Cambridgeshire to be on the lookout for toxic algae.
Blue-green algae produce toxins which can be fatal for animals and cause sickness and muscle pain in humans.
The warning comes as the three areas continue to experience drought conditions, in which the algae thrive.
Anyone who sees the blue-green algae, which "bloom" and rise to the water's surface, should contact the EA.
Chris Extence, the EA's environment monitoring team leader, said: "So far, there has only been one confirmed incident of bleu-green algae, near Moulton in Northamptonshire.
"However, because of the potential risks associated with blooms, we are asking people to be vigilant and to keep pets and children away from water they suspect may contain the algae," he said.
Blue-green algae (Cynobacteria) occurs naturally in rivers, ponds, estuaries and the sea.
Excess nutrients, which may result as water levels drop, can increase the chances of a bloom.
Blooms can look like paint, jelly or form small clumps and may be blue-green, grey-green, greenish-brown or reddish-brown in colour.
Mr Extence added: "Not all blue-green algae blooms are toxic but you can't tell by just looking at them, so it's best to assume they are and to take suitable precautions."