Tonbridge Bean

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If you’ve recently spotted a green tinge in the River Medway as it winds through Tonbridge, you’re not alone. Local residents may have noticed a change in the appearance of the water — and there’s now confirmation as to why.

Following previous reports of blue-green algae in Haysden Water, the Environment Agency has now confirmed the presence of the algae near Town Lock on the River Medway in Tonbridge. In a “Notice to Mariners” issued on 28 July, the Medway Navigation team advised that the algae has been identified at Town Lock, and that similar occurrences are likely to appear elsewhere along the Medway Navigation.

What is Blue-Green Algae?

Blue-green algae are naturally occurring organisms found in inland waters such as rivers, lakes and reservoirs. During calm, sunny conditions, the algae can rise to the surface and form visible scums. These may look like green or blue-green paint, jelly, or flakes, and can sometimes appear grey, brown, or even reddish in colour. Wind can cause the algae to accumulate near riverbanks or around structures like locks.

These blooms tend to come and go, and while not all are harmful, some types of blue-green algae can produce toxins that are potentially dangerous to both humans and animals.

What Are the Risks?

For humans, contact with toxic blue-green algae can cause skin irritation, eye issues, or more general symptoms such as vomiting, diarrhoea, fever, and muscle or joint pain — particularly for those who swim in or accidentally swallow the water. While there have been no fatalities reported in humans, some cases have been severe.

Of particular concern is the danger to animals. Dogs are especially vulnerable to the toxins and should be kept well away from affected water. If your pet has been in contact with contaminated water and shows signs of illness, contact a vet immediately.

Sensible Precautions

The Environment Agency recommends avoiding contact with any visible scum on the river, and being cautious around water where algae may be present. Even if the water appears clearer on some days, blooms can return quickly and may not always be visible to the naked eye.

As the warmer weather continues, it’s expected that other parts of the Medway may also be affected, so this advice applies along the entire navigation.

Tonbridge Bean will continue to monitor the situation and provide updates as we receive them. In the meantime, enjoy the river safely and stay informed.

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For more updates from the Medway Navigation team, you can visit the River Medway website.

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