Research and analysis

North West water situation: May 2024 summary

Updated 21 June 2024

Applies to England

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

1. Rainfall

There were notable spells of heavy rainfall across north-west England throughout May with a few drier periods in-between. The heaviest rainfall was recorded on the 22 May where the Burnbanks rainfall site observed 102% of its long term average (LTA) for May in 24 hours.

Rainfall across north-west England as a whole was classed as notably high for May with 164% of the LTA. The Cumbria and Lancashire (CLA) area observed 172% of the LTA while the Greater Manchester, Merseyside and Cheshire (GMC) area observed 164% of the LTA, both classed as notably high.

Hydrological areas across north-west England recorded rainfall classed between above normal and exceptionally high. Eden and Ribble were classed as exceptionally high, Esk (Cumbria), Esk (Dumfries) and Kent were classed as above normal, and all other hydrological areas were classed as notably high. The highest rainfall (in terms of the LTA) was observed in Eden with 193% of the LTA making it the fourth wettest May since 1871. The lowest rainfall (in terms of the LTA) was in Esk (Dumfries) with 139% of the LTA for May.

Despite May having less extreme total rainfall than in the preceding 2 months, north-west England still recorded the second wettest 3 months of rainfall ending in May since 1871. This is the case for both GMC and CLA areas. Exceptionally high rainfall in the last 3 months was also observed in all the hydrological areas apart from Esk (Dumfries).

This trend continues in both the 6 and 12 month rainfall distributions with all the hydrological areas with exception of Esk (Dumfries) showing exceptionally high rainfall. Esk (Dumfries) has seen notably high rainfall for the last 6 months and above normal rainfall for the last 12 months. The last 6 and 12 months of rainfall were the wettest ending in May since 1871 for the whole of north-west England including both GMC and CLA areas. All Hydrological areas across the north-west England recorded the wettest last 6 month period of rainfall since 1871 apart from Esk (Dumfries), Eden and Derwent as well as their wettest last 12 month period of rainfall since 1871 with the exception of Esk (Dumfries).

2. Soil moisture deficit and recharge

Soil moisture deficits (SMD) across north-west England had decreased by the end of May when compared with the end of April. This is in response to drier weather at the end of April and the heavy rainfall in the latter half of May resulting in levels falling between 0mm and 14mm with the majority of SMDs recorded being 0mm. All recorded SMDs were lower than expected for the time of year.

3. River flows

Monthly mean river flows across north-west England during May were classed between normal and exceptionally high, mostly decreasing in terms of LTA when compared with flow values recorded during April. Out of the 25 sites 3 were classed as exceptionally high, 6 as notably high, 14 as above normal and 2 as normal.

In response to the heavy rainfall, the highest mean river flow (in terms of the LTA) was observed in Eden with 229% of the LTA and classed as exceptionally high. The lowest mean river flow was in the Lune with 102% of the LTA.

4. Groundwater levels   

Groundwater levels across the north-west England were classed between exceptionally high and normal at the end of May. The groundwater levels at Priors Heyes, Richmond Park and Skirwith remained at the same classification with exceptionally high. They also recorded the highest levels we have on record for the end of May. All other sites recorded as follows:

• Brown Bank Lay-By was classed as notably high increasing from above normal
• Bruntwood Hall classed as above normal decreasing from notably high
• Lea Lane remained at the same classification as normal

Levels at Priors Heyes remain high compared to historic levels because the aquifer is recovering from the effects of historically high abstractions.

5. Reservoir stocks

Total reservoir storage for north-west England fell slightly during the first half of May then increased in response to the heavy rainfall resulting in the same 92% storage as at the end of March. This is higher than the average of 86% total storage for the time of year and also higher than the storage of 85% seen at the end of May last year.

At the end of May, the reservoirs with the highest storage (in terms of percentage) were at Crummock Water, Ennerdale Water and Vyrnwy which were all 100% full. The lowest storage was at Rivington Group with 78%. The combined storage at Haweswater and Thirlmere was 95% which is higher than the average storage of 78% at this time of year and also higher than the storage of 82% seen at the end of May last year.

There were a number of reservoirs kept low for maintenance works including:

• Audenshaw No.1
• Torside
• Woodhead
• Anglezarke
• High Bullough
• Dingle
• Jumbles
• Harlock
• Kitcliffe
• Llyn Celyn
• Ogden Lower
• Ogden Upper
• Alston No.2
• Ridegate
• Cragg

Author: Greater Manchester, Merseyside and Cheshire Hydrology Team, hydrology.GMMYCH@environment-agency.gov.uk

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