June 2024 Blue Green Algae samples exceeded WHO limits for recreational use of Windermere

On 25th June, just weeks before the school holidays begin in the Lake District, we were alerted to a blue-green algal bloom at Waterhead, described as ‘extensive’. On arrival, the bloom extended roughly 100m along the shoreline, stretching between 5-10 metres into the lake, and we observed people swimming in the water near the bloom. We took four samples: three along the worst affected area of the bloom and one away from the worst affected area, which at the time of sampling was deemed un-impacted by the bloom.

The samples demonstrated cyanobacteria concentrations that exceeded the World Health Organisation (WHO) limits for recreational use of the lake. This is the second time in 2 years the campaign had deemed the risk to human health as a justifiable reason to undertake independent sampling at Waterhead. Both times the WHO threshold has been surpassed.

The three samples taken in the worst affected area were well above the EA Warning (Signing) threshold of 500-700 gyres/ml and the WHO Recreational Limit of 100,000 cells/ml:

Sample 1: 666,846 cells/ml
Sample 2: 772,182 cells/ml
Sample 3: 809,298 cells/ml

The fourth sample was still above the EA warning threshold, despite appearing less impacted, but was below the WHO recreational limit.

Toxin analysis was also undertaken on the samples. In this case, toxins were not being produced at the time of analysis. However, expert consensus is that BGA produces toxins 60-70% of the time when a bloom is present. Despite this the EA has not conducted any toxin analysis of BGA on Windermere since 2016.

The samples were analysed by the independent, internationally recognised, and published algologist Dr. Nick Everall, ex-Principal Biologist at Severn Trent Water and registered expert witness. The analysis reaffirms our stance that the Environment Agency’s monitoring, warnings, and actions with regards to BGA on Windermere are woefully inadequate, not fit for purpose and pose a risk to public health. Through Freedom of Information requests, the campaign discovered that the Agency takes a reactive approach to BGA monitoring on Windermere, which falls short of WHO guidance:

The WHO’s guidance states:

“While verification monitoring for toxic cyanobacteria should also occur regularly, sampling and analyses may be reduced to seasons in which they are known to occur or human exposure is likely (e.g., the bathing season). Particularly for the monitoring of bathing sites at which cyanobacteria are known or likely to occur, a high frequency of sampling (i.e., daily or weekly) may be necessary for relatively short periods during the peak bathing season.”

The area sampled is not classed as a bathing water, but is used frequently for recreational activities, including swimming. It is also a known hotspot for BGA. Thus Save Windermere calls for the new Environment Minister, Steve Reed, to instate permanent signage around the shores of Windermere and for regular monitoring by the Agency to be undertaken throughout the summer season across the whole lake. Save Windermere returned to the same location on June 26th, and the bloom had dissipated, emphasising the need for routine monitoring of the lake. We have not been alerted to a bloom in the area since. This bloom occurred during the few days of calm and warm weather in late June, which emphasises that the frequency of blooms is only likely to increase as the risk of climate change induced droughts increases.

Save Windermere has previously challenged bathing water quality classifications on Windermere, claiming they are misleading, with the absence of sampling and monitoring of BGA being a primary reason for this. The campaign believes that all sites where there is public access to the lakeshore should have mandatory warning signs throughout the summer months to ensure bathers can make an informed decision about entering the water.

Although BGA can be potentially fatal to humans, cases of human fatality are rare as most humans do not drink raw water from surface waters and ingestion of the quantity required would likely only occur in an incident of drowning. Domestic animal poisoning is more common, for example in dogs and cattle, which can take in large amounts of poisonous algae when drinking or, in the case of dogs, cleaning their coats of scum after swimming in algal laden margins of lakes and ponds.

We deem all previous investment by United Utilities to be insufficient to ensure the lake is adaptable to climate change. Despite previous reduction of phosphorus concentrations, United Utilities is still the single largest input of the nutrients that feed algae growth in Windermere. This comes after United Utilities paid the highest dividend in the country last year at £454 million and has accrued £8.9 billion in debt in the 35 years since privatisation.

We are calling for a complete end to sewage discharging into Windermere and have recently called on all political parties to grant Windermere greater protection as the only way to ensure the long term protection of England's largest lake. In the face of a changing climate these blooms are going to become an increasing concern. Not enough has been done to protect Windermere and ensure its long term health. This is as much about the failure of the regulator as it is of the water company. We call for the new government to instate our 10-point plan for a sewage free Windermere

Dr Nick Everall had this to say:

“Sixty to seventy percent of blue-green algal blooms produce toxins and other bi-products which can cause allergic skin reactions and vomiting sickness when ingested by humans. People would do well to remember that, weight for weight, the toxins produced by these organisms are as toxic as cobra venom if ingested. Certainly monitoring of recreational waters should be adequate to protect all water users and allow them to make their own informed decisions on health and safety.“