Research and analysis

Devon and Cornwall water situation: June 2024 summary

Updated 12 July 2024

Applies to England

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

1. Summary

Devon and Cornwall received 49% of the long term average (LTA) rainfall, which was below normal for the time of year. It was the second wettest October to June period in a record starting in 1871. Soil moisture deficit (SMD) increased overall in June and ended the month higher (drier) than the LTA for the time of year. Monthly mean river flows ranged from below normal to above normal for the time of year across the area. Groundwater levels at all sites receded overall in June, but still ended the month at normal to exceptionally high for the time of year. Total reservoir storage across Devon and Cornwall ended the month at 89% net storage, with Wimbleball, Colliford and Roadford reservoirs at 88%, 92% and 94% of net storage respectively at the end of June.

2. Rainfall

Devon and Cornwall received 34mm of rain during June (49% of the June LTA), which is classed as below normal for the time of year. Despite a drier than average June, it was the second wettest October to June period in a record starting in 1871. The most significant periods of rain occurred on 13 to 15 June, and on 21 June, with very little rain in the remainder of the month. In June, rainfall for this time of year was:

• below normal for the time of year in most hydrological areas
• normal for West Cornwall
• notably low for the Exe, Teign and Torbay, and Otter, Sid, Axe and Lim hydrological areas

In the last 6 and 12 months, cumulative rainfall totals were exceptionally high in all hydrological areas when compared to historic respective totals.

3. Soil moisture deficit

SMD increased (soils became drier) over June. By 25 June the average deficit for Devon and Cornwall was 41mm to 70mm, and was higher (soils were drier) than the LTA for the time of year. The SMD was lower (soils were wetter) than the deficit at the same time in 2023.

4. River flows

June monthly mean river flows were normal for the time of year across most sites. The river Hayle at St Erth experienced above normal June flows for the time of year. The river Camel at Bodmin Dunmere and the river Taw at Umberleigh experienced below normal June flows for the time of year. Daily mean river flows experienced a downward trend throughout the month at all sites in response to the lower than average rainfall. On 30 June, all reporting sites recorded below normal or normal daily mean flows for the time of year.

Due to data accuracy concerns, Gunnislake gauging station on the river Tamar is not reported on this month.

5. Groundwater levels   

Levels at all groundwater sites receded overall in June. On 30 June, groundwater levels were exceptionally high at the following sites:

• Branscombe Lane (monitoring the Dawlish Sandstone)
• Bussells No7A (monitoring the Dawlish Sandstone)
• Coleford Production (monitoring the Permian Breccias and Sandstones)
• Whitlands (monitoring the Upper Greensand)
• Woodbury Common No2 (monitoring the Budleigh Salterton Pebble Beds)

Levels at Winnards Perch (monitoring the Staddon Formation) and Woodleys No1 (monitoring the Otterton Sandstone Formation) were classed as normal and notably high respectively on 30 June.

6. Reservoir stocks

Total reservoir storage was 89% at the end of June, which is a reduction of 9% of storage since the end of May. This is higher than total storage at the same time last year and in 2022.  At the end of the month, storage at Wimbleball, Colliford and Roadford reservoirs was 88%, 92% and 94% of net storage respectively, compared to 88%, 63% and 65% this time last year.

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.