December water quality results
December Sampling Update
This December, our water quality monitoring captured the impacts of heavy rainfall and active sewage spills across the Dart catchment. Sampling focused on the main River sites, including community-designated locations and designated bathing waters, as well as a few new sites to inform future monitoring.
2nd December – First Wet Weather Sampling Round
Following 58.4mm of rain and active or recent spills at most CSOs along the River Dart, we collected samples from the main River sites. Road flooding on the Old Road between Totnes and Buckfastleigh prevented sampling at Old Road 1 and 2.
E. coli concentrations were low at Holne Weir, the Mardle, and Old Road 3. Dartington Beach and Dartington Pontoon showed relatively low levels compared to past results. Still Pool recorded its second-highest E. coli concentration since monitoring began, though with only four samples collected so far, it remains too early to draw conclusions.
High E. coli levels were observed on the Ashburn River and at Steamer Quay, with Dittisham and Warfleet Creek also showing elevated concentrations. These results likely reflect the combined effects of sewage spills following rainfall alongside agricultural runoff.
E. coli concentration (cfu/100ml):
Holne Weir - 0
Ashburn - 18,500
Mardle - 200
Old Road 3 - 200
Still Pool - 2300
Dartington Beach - 1200
Dartington Pontoon - 1300
Steamer Quay - 11,000
Dittisham - 2500
Warfleet Creek - 2700
10th December – Storm Bram Sampling Round
Following around 60mm of rainfall from Storm Bram, with many CSOs spilling across the catchment from Princetown down to Dartmouth, we completed a further round of sampling. At Stoke Gabriel, samples were collected on the ebb tide (high tide 9:10am) to better understand bacterial movement through the estuary.
Key Findings
Ashburn & Mardle
The Ashburn showed high E. coli levels, consistent with active spills in Ashburton. The Mardle had lower concentrations, suggesting earlier spills in Buckfastleigh had already moved through the system.
New Sites: Malt Mill Lake
Two new sites were tested to evaluate their suitability for ongoing monitoring. Levels were not concerning, though a slight increase between upstream and downstream points suggests a local input, possibly a permitted discharge or misconnections. Malt Mill Lake will likely be included in winter investigations.
Stoke Gabriel & Mill Pool
An additional site at Mill Pool helps track how bacteria from the Yalberton Stream moves through the system. Mill Pool showed high E. coli levels, likely reflecting an active spill below the sampling point. Stoke Gabriel bathing water also showed elevated concentrations, unsurprising given active spills from the Scout Hut CSO and Stoke Gabriel Pumping Station. With Stoke Gabriel classified as “Poor” this bathing season (down from “Sufficient”), we will increase winter sampling to support the Environment Agency’s planned investigations ahead of next summer.
E. coli concentration (cfu/100ml):
Ashburn - 13,000
Mardle - 1800
Malt Mill Lake (MML) US - 1100
MML DS - 2200
Mill Pool - 19,500
Stoke Gabriel - 5000
Looking Ahead
We are currently in the process of summarising our key takeaways from tributary monitoring across the Dart catchment. Alongside this, we are drafting a revised testing protocol focused on high-priority tributaries that appear to have the most significant impact on water quality in the main River. This will help guide future monitoring and interventions to target pollution sources most effectively.