Toxic algae found in Grantham Canal and Denton Reservoir

Grantham Canal.
Grantham Canal.
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A charity is warning people to avoid contact with the water in Grantham Canal and Denton Reservoir after a toxic algae was discovered.

The Canal and River Trust is advising visitors to avoid contact with the water due to an outbreak of blue-green algae.

The algae is naturally occurring in summer, but it can be harmful to the skin, causing allergic reactions including itchy eyes, skin irritation and hay fever-like symptoms.

The algae has been spotted in Denton Reservoir and the adjacent canal and the Trust is encouraging visitors, their children and pets to avoid contact with the water. Warning signs have been placed around the affected areas.

Occasionally, blue-green algae ‘blooms’ can turn the water green, blue-green or greenish brown and sometimes cause paint-like or jelly-like scums.

The Trust – which cares for the reservoir and the Grantham Canal that it feeds – is monitoring the algae levels and deciding on the most effective way of dealing with it.

Sean McGinley, Canal and River Trust waterway manager, said: “The Grantham Canal and Denton Reservoir are really popular placs for angling and also people walking, cycling or enjoying the local nature. We want people to continue to enjoy the lovely waterside setting but to be aware that there’s a current outbreak of blue-green algae in the water.

“Blue-green algae is naturally occurring but it can be harmful to your skin. We’re asking people to be extra careful and if they or their pets come into contact with the affected water, they should wash all exposed skin with clean water as soon as possible, and particularly before eating or drinking. If they are in any doubt about their health after contact with algae, they should seek medical advice.

“We’re monitoring the levels of the algae and deciding whether it is best to let it die off naturally or treat it directly.”

For more information about the Canal and River Trust visit