Wet and Dry weather sampling

Summary of Wet and Dry sampling over September

Our first two wet weather monitoring rounds of September highlighted the ongoing impact of rainfall, runoff, and combined sewer overflows (CSOs) on water quality in the Dart catchment. Later in the month, a spell of sunshine gave us the chance to collect dry weather samples across all of our sites — offering a valuable contrast and a clearer picture of where pollution problems persist.

3 September — First Wet Weather Round

Following 29 mm of rain in the 24 hours before sampling, tributary sites including Old Mill Leat, the AM Brook, and the Hemms all recorded extremely high E. coli concentrations. Every site fell into the “Poor” category against Environment Agency bathing water thresholds.

The highest results were found on the Hemms and AM Brook, which are now the focus of targeted walkover investigations. These results coincided with 36 CSO spill events in the previous 24 hours, with four assets — including Kilbury and Totnes sewage treatment works — still discharging at the time of sampling.

11 September — Second Wet Weather Round

The second wet weather round focussed on the main River Dart. Upstream of Totnes, water quality was comparatively good, with record-low wet weather results at sites around the Dartington Estate.

In contrast, E. coli concentrations at Steamer Quay were extremely high, likely reflecting both local CSO spills and inputs from the Bidwell Brook and Hemms. Elevated results were also found on the Harbourne and Bow Creek, potentially linked to a spill from Harberton STW.

23–24 September — Dry Weather Sampling

We made the most of the September sunshine to collect dry weather samples across all of our monitoring sites over two days. The results gave a mixed picture:

• Excellent water quality (<500 cfu/100ml):
  Holne Weir, Ashburn, Old Road 1, Old Road, Harbourne, Bow Creek, and upstream sites along Old Mill Leat.
  
  

• Good water quality:
  Rattery Stream, the Mardle, Staverton Bridge, upstream of Broadhempston STW on the River Hemms, and both sampling sites on the AM Brook.
  
  

• Sites of concern:
  Tripes Copse and Torbryan, which feed into the AM Brook (and eventually the River Hemms), once again recorded elevated E. coli levels. These sites have consistently shown poorer results across our monitoring period. As the Hemms joins the Dart just below Totnes Weir, this area will remain a focus for investigative monitoring in the coming months. Planned walkovers will help us build more detailed spatial data to identify likely sources of pollution.
  
  

Community bathing sites:
Still Pool (Staverton), Dartington Beach, and Dartington Pontoon — all popular local swimming spots — unfortunately showed elevated E. coli levels and were classed as “Poor” for water quality this month.