More than 76,000 sewage spills hit Scotland’s waterways last year after new monitoring equipment was installed at waste overflow sites.
The installation of 1,009 sewer monitors in 2024 expanded the portion of the Scottish Water network under surveillance from 6% to 30%, according to BBC analysis. That wider net exposed tens of thousands of discharges that previously went unrecorded, including hundreds at major beauty spots like Loch Lomond.
Glasgow’s River Clyde ranked among the hardest-hit waterways across Scotland last year, receiving almost 6,150 spills, which translates to roughly 17 discharges a day. When including the Clyde Estuary, the Firth of Clyde, and local tributaries, that total nearly doubles to 14,200 spills, or 39 daily.
The Clyde Estuary also registered the longest duration of releases at more than 25,000 hours. The River Clyde followed with over 15,000 hours of discharges. Meanwhile, Barcloy Mill Burn in Dumfries and Galloway recorded nearly 3,500 spills, which is one of the newly-monitored sites.
Just under 12% of sewer overflows carry a legal requirement to report data to the Scottish Environment Protection Agency (Sepa). The regulator operates with “a risk-based approach” that prioritizes monitoring areas by population size and environmental need, though none of the newly added monitors were mandated to report to Sepa.
Across the entire network, Scottish Water recorded more than 100,000 spills totaling almost 277,000 hours last year, averaging about 274 a day. Officials note that assessing year-over-year comparisons remains difficult because lower coverage yielded only 24,000 recorded spills previously.
In West Lothian, local campaigner Ruth Plevin voiced concern over invisible pollutants entering the 28-mile River Almond, which recorded 1,270 spills totaling nearly 1,500 hours last year.
“It’s what’s not visible that is our concern – the microplastics, the pharmaceuticals, the agrichemicals, stuff that you can’t see,” she said.
Ruth Plevin, member of the River Almond Action Group
Further down the east coast at Belhaven in East Lothian, Brian Allen, the regional representative for Surfers Against Sewage, described the findings as “really good news” for the area after discovering that 86% of tested samples were rated as excellent, good or sufficient water quality, with 77% of the results coming back as excellent.
Scottish Water maintains that 99% of spills consist of rainwater, surface water, road runoff, household grey water, groundwater infiltration, and trade effluent rather than raw human sewage.
Simon Parsons of Scottish Water said the expanded monitoring network had improved understanding of the sewer network and helped identify locations requiring improvement. He said that Scottish Water did not necessarily know how and when overflows were operating, so they have a much better picture now than ever before, and can actually identify those areas where they need to think about investment.
While Scottish monitoring trails England’s 100% coverage, Scottish Water reported that its own network coverage has now grown to about 50%, with a target to achieve 100% coverage over the next five to six years.
