The Environment Agency has issued a warning against swimming in London's first official bathing site at Kingston upon Thames due to toxic blue-green algae. The agency has also advised locals to avoid entering the water along a broader stretch of the river likely affected by the bloom, and stressed it is 'vitally important' to keep dogs away.
Health risks from cyanobacteria
The blue-green algae, scientifically known as cyanobacteria, can produce toxins harmful to human and animal health. These plant-like organisms can quickly grow out of control, especially when warm temperatures, low rainfall, and calmer water conditions create ideal growing environments. Some blooms generate toxins capable of killing wild animals, farm animals, and pets, and can cause skin rashes and illness in humans if swallowed.
According to the Environment Agency, during drought and prolonged dry weather, it has reported increasing numbers of algal blooms, fish deaths, and deteriorating water quality. Currently, around three-quarters of England is in drought following five heatwaves and temperatures exceeding 38.1°C.
Official warnings and signage
A spokesperson for the Environment Agency stated: 'We have identified blue-green algae on the lower River Thames, including the Ham and Kingston designated bathing water. We are working with the Royal Borough of Kingston upon Thames, who have put signage in this location to warn people that it is not safe to swim.'
The spokesperson added: 'An advice against bathing notice has been activated on the Swiminfo website.' They also warned that the section of the River Thames between Hampton and Kingston had likely been affected. 'It is important that members of the public do not enter the Thames along this stretch. It is also vitally important to keep dogs out of the water,' the spokesperson urged.
Monitoring and impact
The Environment Agency is taking water samples along the stretch of river to confirm the extent of the algal bloom. Abstractors downstream and the UK Health Security Agency have been notified. The Ham and Kingston bathing site opened in May as part of the latest tranche of new spots for open-water swimming, becoming the first designated bathing water on the river in London. It is subject to regular water tests during the summer season until the end of September.
