Research and analysis

Devon and Cornwall water situation: August 2026 summary

Updated 14 September 2026

Applies to England

• Publication for Northern Ireland
• Publication for Scotland
• Publication for Wales

1. Summary

Devon and Cornwall received 68mm of rain during August. This is 72% of the August long term average (LTA), which is normal for the time of year. Soil moisture deficit (SMD) remained higher (drier) than the LTA throughout August. August monthly mean flows ranged from exceptionally low to below normal across the area. Groundwater levels ended the month between exceptionally low and exceptionally high for the time of year. Total reservoir storage across Devon and Cornwall on 30 August was 48%, with Wimbleball, Colliford and Roadford at 34%, 49% and 55% respectively.

2. Rainfall

Devon and Cornwall received 68mm of rain during August (72% of the August LTA), which is normal for the time of year. Rainfall was minimal across the area during the first two weeks of August, with 95% of the month’s total falling thereafter.

All of Cornwall, alongside the Torridge and Hartland Streams, and Avon Dart and Erme hydrological areas recorded normal rainfall for the time of year. The remaining hydrological areas recorded below normal rainfall.

Cumulative rainfall for the last 3 months was below normal across most of the area. The Otter, Sid, Axe and Lim, Teign and Torbay and Exe hydrological areas recorded notably low rainfall. Over the last 6 months, cumulative rainfall was notably low for the majority of the area. The Otter, Sid, Axe and Lim, Taw and North Devon Streams, Teign and Torbay and Exe hydrological areas recorded exceptionally low rainfall. Over the last 12 months, cumulative rainfall was above normal to exceptionally high across the area.

3. Soil moisture deficit

SMD in Devon and Cornwall increased (soils became drier) during August. SMD exceeded the maximum for the time of year on 11 August, and exceeded the maximum for the full period of record on 25 August. SMD then decreased (soils became wetter) in response to the rainfall at the end of the month but was still higher (drier) than the LTA.

By the end of August, SMD was 131mm to 160mm in the following hydrological areas:

• Otter, Sid, Axe and Lim
• Exe
• Torridge and Hartland streams
• North Cornwall

Across the rest of the area, SMD was 101mm to 130mm. SMD in the Taw and North Devon Streams, Torridge and Hartland Streams, North Cornwall and Tamar hydrological areas was more than 75mm above the LTA. The rest of the area was 51mm to 75mm higher than the LTA.

4. River flows

August monthly mean flows were below normal to exceptionally low across the area. The River Teign at Chudleigh recorded the lowest August monthly mean flow on record.

Daily mean flows decreased at all sites through the first half of the month in response to continued dry weather. By mid-month, the rivers Teign at Chudleigh, Hayle at St Erth and Gannel at Gwills had all recorded lowest flows for the time of year. Rainfall in the latter half of the month allowed river flows to recover, and by 31 August, daily mean flow was normal across most of the area. Bodmin Dunmere recorded below normal and Gwills and St Erth recorded notably low.

5. Groundwater levels   

On 31 August, groundwater levels were classed as follows:

• exceptionally low at Winnards Perch (monitoring the Staddon Formation)
• below normal at Coleford Production (monitoring the Permian Breccias and Sandstones)
• normal at Bussels No7A (monitoring the Dawlish sandstone), Woodleys No1 (monitoring the Otterton Sandstone Formation) and Woodbury Common No2 (monitoring the Budleigh Salterton Pebble Beds)
• above normal at Branscombe Lane (monitoring the Dawlish Sandstone)
• exceptionally high at Whitlands (monitoring the Upper Greensand)

Groundwater levels are much lower at the ‘Secondary Aquifer’ sites (Winnards Perch and Coleford Production) than at the other sites, which are in ‘Principal Aquifer’. This is because Secondary Aquifers have lower storage and respond more rapidly to a lack of recharge from rainfall.

6. Reservoir stocks

Total reservoir storage was 48% on 30 August, which is an overall decrease of 17% since the end of July. This is higher than storage at the end of June 2022 (the most recent drought year), which was 40%. On 30 August, storage at Wimbleball, Colliford and Roadford was 34%, 49% and 55% respectively, compared to 36%, 31% and 47% at the same time in 2022.

Author: Devon and Cornwall Hydrology, hydrology.dandc@environment-agency.gov.uk

All data are provisional and maybe subject to revision. The views expressed in this document are not necessarily the views of the Environment Agency. Its officers, servants, or agents accept no liability for loss or damage arising from the interpretation or use of the information, or reliance upon views contained in this report.