Environment Agency report for 2025
The Environment Agency Shares Water Data From The Dart
The Environment Agency has shared their water data report for 2025 with Friends of the Dart. The 2025 monitoring year along the River Dart and its tributaries reveals a complex picture of faecal indicator organism (FIO) loading, shaped by agricultural runoff, wastewater infrastructure pressures, and the complications caused by rainfall.
Across the water system, the pattern is familiar but sharper this year: hotspots appear upstream, which are then compounded downstream, with the Hems, Malt Mill Lake, and Bidwell Brook acting as major contributors to declining water quality at Steamer Quay. Similar dynamics play out at Stoke Gabriel arm, where the decline in water quality could be due to poor water quality upstream.
The Dart: Spikes in Enterococci and E. coli.
Between Totnes Weir and Steamer Quay, both E. coli and Intestinal Enterococci appear to spike. The increases closely mirror conditions observed in the Hems and Malt Mill Lake - two tributaries flagged for further investigation in 2026. Bidwell Brook continues to show elevated concentrations, reinforcing the call for targeted improvements within its sub-catchment.
Bidwell Brook: Contamination already high by Shinners Bridge
By the time the water reaches Shinners Bridge, FIO levels are already significantly elevated. There’s a further rise in Intestinal Enterococci by Dartington Lodge, most likely linked to diffuse agricultural inputs. Microbial Source Tracking (MST) data from South West Water show both agricultural and human signatures in the mix, underscoring the need to address both farmland and wastewater-derived sources.
The Hems: A consistent driver of poor water quality
The Hems stands out due to consistently elevated levels across all monitoring points, with Bow Bridge in particular carrying very high loads. Despite a dry summer (conditions that often reveal point-source issues because of the lack of rainfall) FIO levels remained persistently high. MST results from Bow Bridge identify both human and ruminant contributions. As a result, improvements at Broadhempston Wastewater Treatment Works (WWTW) are recommended for review.
Malt Mill Lake: Deterioration without mapped drainage
Water quality declines as the stream moves between its two monitoring points, despite the absence of mapped surface water drains. MST on a highly elevated sample detected a strong human signature, suggesting septic tanks or misconnections as probable sources. A catchment walkover is planned for 2026 to try and determine where the pollution is coming from.
Stoke Gabriel: Upstream issues overshadow downstream recovery
On the Stoke Gabriel stream, upstream concentrations were markedly worse than downstream ones. Reductions of over 9,000 CFU/100ml for both E. coli and Enterococci indicate that the principal issues lie above Tor Park. MST confirmed both ruminant and human markers, with dog sources playing a minimal role. Rainfall-adjusted confidence intervals highlight a sharp contrast between wet and dry day results.
South West Water assets: Storm spill patterns and infrastructure implications
Several wastewater assets - particularly Rattery WWTW, Broadhempston WWTW, Ipplepen, and Denbury - recorded extensive spills in 2024 and multiple events during the 2025 bathing season. Some of these events did not coincide with Environment Agency sampling, suggesting missing data on their overall impact. Tor Park Pumping Station, although not currently linked to the bathing water, appears close enough (3 km) and impactful enough during storm events to warrant formal linkage.
On-the-ground investigations: Walkovers and ammonium finds
Walkovers at Stoke Gabriel revealed surface water outfalls with elevated ammonium and possible misconnections. These field observations add weight to the MST-detected human and ruminant signals.
Conclusion: Where to focus in 2026
The report concludes that the primary contributors to microbiological pollution across the Dart system are:
diffuse agricultural inputs
wastewater infrastructure (CSO spills and final treated effluent quality)
septic tanks and misconnections
Targeting interventions in the Hems (especially above Bow Bridge), Bidwell Brook, and Malt Mill Lake is expected to yield the greatest benefit for improving bathing water quality at Steamer Quay.
Friends of the Dart welcomes this report which you can read in full here.