Sewage was discharged into seas around Scotland for more than 113,000 hours last year painting a “terrible picture”, a leading ocean charity warned.
Analysis by the Marine Conservation Society (MCS) believes the amount of sewage dumped is likely to be more as less than 4% of the country’s storm overflows - 123 out of a total of 3,617 - are currently monitored for spills.
The charity said it still doesn’t know “quite how bad it is” and is calling on the Scottish government to demand Scottish Water monitor and report on all discharges from storm overflows by 2026 at the latest, and set progressive spill reduction targets to tackle the problem.
The charity said its research, using data from Scottish Water and the Scottish Environment Protection Agency (Sepa), showed untreated sewage was also released into designated bathing sites as well as marine protected areas.
It found sewage was released into waters within 1km of areas designated for marine nature conservation for more than 20,000 hours last year.
Less than 2% of storm overflows within the same distance of designated bathing waters are monitored yet they alone released sewage for more than 600 hours in 2022, the charity found.
Laura Foster, head of clean seas at the MSC, said: “All we have is a tiny snapshot of data for storm overflows in Scotland, but from what we can see, they paint a terrible picture of the situation.
“For thousands of hours each year, untreated sewage is being released straight into Scotland’s seas. This includes into designated bathing sites as well as marine protected areas which have been specifically recognised for their environmental importance.”
The charity is asking people to email their local MSPs to highlight the issue and lobby them to bring about change.
Catherine Gemmell, Scotland conservation officer at the MCS, said: “By setting progressive targets to reduce sewage pollution, and ensuring they are met by increased monitoring and the required enforcement, the Scottish Government can help protect our seas and the life within it.”
The new analysis comes a year after volunteers from the charity recorded and removed more than 35,000 sewage-related items from Scottish beaches.
But a Scottish Water spokesperson insisted the majority of Scotland’s waterways are among the best quality in Europe. It said it is “not true to call spills from the waste network sewage spills” as the “toilet sewage element of the water that spills is less than 1% of the total volume.”
The spokesperson added: “What is spilled is largely rain water. But the overflows that spill are needed so that water doesn’t back up into homes, streets, business and communities.
“These overflows represent huge volumes of rainwater being safely transferred away from homes and businesses and back safely to the environment to minimise the impacts of extreme weather.”
A Scottish Government spokesperson said it “takes sewage pollution incidents very seriously” and is not “complacent”.
They said that some 66% of Scotland’s water environment meets ‘good’ ecological status, whereas Environment Agency figures for England are only 16%.
They added: “Scottish Water remains on track to deliver on its commitment set out in the Routemap to install at least 1000 new monitors on the network by the end of 2024, with an aim to increase this to 2,500 in the same period.”